Add test and fix for edgecase

Initially only binary output

CONTRIBUTING.md

@@ -16,10 +16,22 @@ All functions in the standard library should follow the following outline:
 ; Arguments: <which register contains what argument>
 ; Result: <what is the result, and where is it stored>
 ; Clobbers: <list of registers that are clobbered>
+; Globals: <list of globals are accessed. OPTIONAL>
+; Errors: <list of any status codes returned in flags. OPTIONAL>
 <label>: <;SHOULD BE INLINED>
     <CODE>
 
 ```
 
 Functions should be in the appropriate asm file, if you are unsure where functionality fits make a seperate file and ask in the pull request
-Functions that are provided for convenience/reference but should be inlined in production code should be marked with `;SHOULD BE INLINED` after their label
+Functions that are provided for convenience/reference but should be inlined in production code should be marked with `;SHOULD BE INLINED` after their label.
+
+If the function returns a status code in flags, the preamble should list all it might return.
+
+## Globals
+
+Any function that uses global variables should document this in the preamble comment, see above.
+
+A file/module should check on intialisation that the address `globals.MAGIC_ADDRESS` contains the 16 bit value `globals.MAGIC_VALUE`, to ensure that the user has properly included [[src/start.asm]] and reservered the global variable area.
+
+No opinion is offered on whether modules can assume globals variables are initialised to zero.

README.md

@@ -3,7 +3,7 @@
 This is a standard library for symphony.
 It is both intended as a practical toolkit to develop more complex software as well as a teaching resource.
 
-If you just want to use the standard library [[stdlib.asm]] is your main header, include it after your code.
+If you just want to use the standard library [[src/stdlib.asm]] is your main header, include it after your code. Some modules also require [[src/start.asm]] at the very start of the program.
 
 If you are using it as a learning resource have a look at the [teaching folder](teaching).
 
@@ -20,7 +20,7 @@ If you are intersted in contributing have a look at [[CONTRIBUTING.md]]
 | preserved | sp, r8 - r12 |
 | scratch | flags, r1 - r7 |
 | arguments | r1 - r7 |
-| result | r1-r7 |
+| result | flags, r1 - r7 |
 | return address | r13 |
 
 Arguments not fitting into the 7 registers should be passed on the top of the stack, meaning they should be the last values pushed before the function call.
@@ -32,9 +32,14 @@ Should a function return more values than fit into the 7 registers, the caller h
 This reduces the amount of argument registers to 6 and all arguments above that shall go on the stack, the pointer to the result stack shall **always** be passed in an argument register.
 This register points at the highest available address for results, with the 8th result being stored there, the 9th below it and so on.
 
+Some functions return a success/failure status code in flags. A set low bit will indicate some error condition, the function may return more than one possible value to report different errors. A flags value of 0 is set on success. No other even values are used. This can be checked with `je` or `jne` immediatly on return to the caller. All other functions clobber flags.
+
 ### Stack
 Grows downwards from 0xXXFE_0000 (so top of memory -0x1_0000).
 
+### Globals
+Global variables are stored near the bottom of RAM in the address range 0x0010..0x0100. Programs should `include src/start` as the first line before their own code and before other includes, or otherwise reserve this space, the first instruction should be a jump to user code.
+
 ### Types
 
 #### String

examples/README.md

@@ -0,0 +1,3 @@
+# Examples
+
+Examples of how to use the standard library to accomplish a task.

isa/README.md

@@ -0,0 +1,43 @@
+Symphony ISA specs for use in stdlib
+
+# `default.isa`
+The stock game ISA. Production code must comply to this. Taken from `symphony_11_functions` in game version 2.1.330A
+
+# `test.isa`
+ISA with additional instructions. These additional instructions may be used in
+the tests directory only. Some of these instructions require hardware changes.
+
+## Labels in more instructions
+
+`cmp`, `load`, and `store` instructions (but not `pload` and `pstore`) now also accept labels.
+
+## `qcall %a(label)`
+Performs a jump-and-link function call, with label size up to 32 bits.
+
+_HARDWARE:_ Store PC+4 in the result register when in jump mode.
+
+## `li %a(register) %b:U32(immediate | label)`
+Loads an immediate up to 32 bits long
+
+_HARDWARE:_ No requirements
+
+## `halt%c(condition)`
+Halts if `flags` matches the condition.
+
+_HARDWARE:_ Halt if instruction bit 31 is set AND the condition block is true.
+
+```
+condition
+""     1000
+".all" 1000
+".e"   0001
+".ne"  1001
+".b"   0010
+".ae"  1010
+".be"  0011
+".a"   1011
+".l"   0100
+".ge"  1100
+".le"  0101
+".g"   1101
+```

isa/default.isa

@@ -0,0 +1,316 @@
+[settings]
+name = "Symphony"
+
+[fields]
+
+register
+zr 0000
+r1 0001
+r2 0010
+r3 0011
+r4 0100
+r5 0101
+r6 0110
+r7 0111
+r8 1000
+r9 1001
+r10 1010
+r11 1011
+r12 1100
+r13 1101
+sp 1110
+flags 1111
+
+[instructions]
+
+nop
+00000000 00000000 00000000 00000000
+# (31337_88272577071256, `Does nothing.`)
+
+in %a(register)
+00000001 aaaa0000 00000000 00000000
+# (31337_44524771082050, `Loads an input and stores it in %a.`)
+
+out %b(register)
+00000010 00000000 0000bbbb 00000000
+# (31337_18254089726214, `Sends %b to output.`)
+
+out %a:U16(immediate)
+00010010 00000000 aaaaaaaa aaaaaaaa
+# (31337_15915531259935, `Sends %a to output.`)
+
+keyboard %a(register)
+00000011 aaaa0000 00000000 00000000
+# (31337_27868418224252, `Loads keyboard input and stores it to %a.`)
+
+screen %a(register), %b(register)
+00000100 0000aaaa 0000bbbb 00000000
+# (31337_39857449355186, `Stores the value of %b in screen setting %a.`)
+
+screen %a(register), %b:U16(immediate)
+00010100 0000aaaa bbbbbbbb bbbbbbbb
+# (31337_12835125621741, `Stores the value of %b in screen setting %a.`)
+
+time_0 %a(register)
+00000101 aaaa0000 00000000 00000000
+# (31337_72551400437977, `Loads the lower four bytes of the time value and stores it to %a.`)
+
+time_1 %a(register)
+00000110 aaaa0000 00000000 00000000
+# (31337_68219187873304, `Loads the upper four bytes of the time value and stores it to %a.`)
+
+counter %a(register)
+00000111 aaaa0000 00000000 00000000
+# (31337_67376584796076, `Loads the counter value and stores it to %a.`)
+
+
+
+nand %a(register), %b(register), %c(register)
+00100000 aaaabbbb 0000cccc 00000000
+# (31337_86705346481666, `NAND %b and %c and stores the result in %a.`)
+
+or %a(register), %b(register), %c(register)
+00100001 aaaabbbb 0000cccc 00000000
+# (31337_40732211165530, `OR %b and %c and stores the result in %a.`)
+
+and %a(register), %b(register), %c(register)
+00100010 aaaabbbb 0000cccc 00000000
+# (31337_85679146831122, `AND %b and %c and stores the result in %a.`)
+
+nor %a(register), %b(register), %c(register)
+00100011 aaaabbbb 0000cccc 00000000
+# (31337_37333076617857, `NOR %b and %c and stores the result in %a.`)
+
+add %a(register), %b(register), %c(register)
+00100100 aaaabbbb 0000cccc 00000000
+# (31337_51030225266712, `ADD %b and %c and stores the result in %a.`)
+
+sub %a(register), %b(register), %c(register)
+00100101 aaaabbbb 0000cccc 00000000
+# (31337_28652904157569, `SUB %b and %c and stores the result in %a.`)
+
+xor %a(register), %b(register), %c(register)
+00100110 aaaabbbb 0000cccc 00000000
+# (31337_46967848572964, `XOR %b and %c and stores the result in %a.`)
+
+lsl %a(register), %b(register), %c(register)
+00100111 aaaabbbb 0000cccc 00000000
+# (31337_13576771671264, `Logical shifts left %b by %c and stores the result in %a.`)
+
+lsr %a(register), %b(register), %c(register)
+00101000 aaaabbbb 0000cccc 00000000
+# (31337_67019902294705, `Logical shifts right %b by %c and stores the result in %a.`)
+
+asr %a(register), %b(register), %c(register)
+00101001 aaaabbbb 0000cccc 00000000
+# (31337_42626144645228, `Arithmetic shift right %b by %c and stores the result in %a.`)
+
+cmp %a(register), %b(register)
+00101010 1111aaaa 0000bbbb 00000000
+# (31337_54565380946620, `Compares %a and %b and stores the result in the 'flags' register.`)
+
+
+nand %a(register), %b(register), %c:U16(immediate | label)
+00110000 aaaabbbb cccccccc cccccccc
+# (31337_75302656449127, `NAND %b and %c and stores the result in %a.`)
+
+or %a(register), %b(register), %c:U16(immediate | label)
+00110001 aaaabbbb cccccccc cccccccc
+# (31337_30574433901064, `OR %b and %c and stores the result in %a.`)
+
+nor %a(register), %b(register), %c:U16(immediate | label)
+00110011 aaaabbbb cccccccc cccccccc
+# (31337_46087142860391, `NOR %b and %c and stores the result in %a.`)
+
+and %a(register), %b(register), %c:U16(immediate | label)
+00110010 aaaabbbb cccccccc cccccccc
+# (31337_86713121915282, `AND %b and %c and stores the result in %a.`)
+
+add %a(register), %b(register), %c:U16(immediate | label)
+00110100 aaaabbbb cccccccc cccccccc
+# (31337_23349431010010, `ADD %b and %c and stores the result in %a.`)
+
+sub %a(register), %b(register), %c:U16(immediate | label)
+00110101 aaaabbbb cccccccc cccccccc
+# (31337_67495552371225, `SUB %b and %c and stores the result in %a.`)
+
+xor %a(register), %b(register), %c:U16(immediate | label)
+00110110 aaaabbbb cccccccc cccccccc
+# (31337_66785854415645, `XOR %b and %c and stores the result in %a.`)
+
+lsl %a(register), %b(register), %c:U16(immediate | label)
+00110111 aaaabbbb cccccccc cccccccc
+# (31337_54577249258785, `Logical shifts left %b by %c and stores the result in %a.`)
+
+lsr %a(register), %b(register), %c:U16(immediate | label)
+00111000 aaaabbbb cccccccc cccccccc
+# (31337_16685334571248, `Logical shifts right %b by %c and stores the result in %a.`)
+
+asr %a(register), %b(register), %c:U16(immediate | label)
+00111001 aaaabbbb cccccccc cccccccc
+# (31337_55551510150818, `Arithmetic shifts right %b and %c and stores the result in %a.`)
+
+cmp %a(register), %b:U16(immediate)
+00111010 1111aaaa bbbbbbbb bbbbbbbb
+# (31337_37102964808364, `Compares %a and %b and stores the result in the 'flags' register.`)
+
+
+jmp %a(register)
+01001000 00001111 0000aaaa 00000000
+# (31337_74148826866592, `Jumps to %a.`)
+
+
+jmp %a:U16(immediate | label)
+01011000 00001111 aaaaaaaa aaaaaaaa
+# (31337_90876214388280, `Jumps to %a.`)
+
+je %a:U16(immediate | label)
+01010001 00001111 aaaaaaaa aaaaaaaa
+# (31337_88180305667389, `Jumps to %a if the values were equal (reading results from 'flags').`)
+
+jne %a:U16(immediate | label)
+01011001 00001111 aaaaaaaa aaaaaaaa
+# (31337_67178948469318, `Jumps to %a if the values were not equal (reading results from 'flags').`)
+
+
+jb %a:U16(immediate | label)
+01010010 00001111 aaaaaaaa aaaaaaaa
+# (31337_31763492459833, `Jumps to %a if the first value was below (unsigned) the second (reading results from 'flags').`)
+
+jae %a:U16(immediate | label)
+01011010 00001111 aaaaaaaa aaaaaaaa
+# (31337_82087388048746, `Jumps to %a if the first value was above (unsigned) or equal to the second (reading results from 'flags').`)
+
+jbe %a:U16(immediate | label)
+01010011 00001111 aaaaaaaa aaaaaaaa
+# (31337_26183125927881, `Jumps to %a if the First value was below (unsigned) or equal to the second (reading results from 'flags').`)
+
+ja %a:U16(immediate | label)
+01011011 00001111 aaaaaaaa aaaaaaaa
+# (31337_11626177279992, `Jumps to %a if the first value was above (unsigned) the second (reading results from 'flags').`)
+
+
+jl %a:U16(immediate | label)
+01010100 00001111 aaaaaaaa aaaaaaaa
+# (31337_71637103729391, `Jumps to %a if the first value was less (signed) than the second (reading results from 'flags').`)
+
+jge %a:U16(immediate | label)
+01011100 00001111 aaaaaaaa aaaaaaaa
+# (31337_53499765587663, `Jumps to %a if the first value was greater (signed) or equal to the second (reading results from 'flags').`)
+
+jle %a:U16(immediate | label)
+01010101 00001111 aaaaaaaa aaaaaaaa
+# (31337_77040234358389, `Jumps to %a if the first value was less (signed) or equal to the second (reading results from 'flags').`)
+
+jg %a:U16(immediate | label)
+01011101 00001111 aaaaaaaa aaaaaaaa
+# (31337_71317192057126, `Jumps to %a if the first value was greater (signed) than the second (reading results from 'flags').`)
+
+
+
+load_8 %dest(register), [%adr(register)]
+01100000 dddd0000 0000aaaa 00000000
+# (31337_57200935026773, `Loads address %adr from main memory and stores it to %dest.`)
+
+load_8 %dest(register), [%adr:U16(immediate)]
+01110000 dddd0000 aaaaaaaa aaaaaaaa
+# (31337_57200935026773, `Loads address %adr from main memory and stores it to %dest.`)
+
+load_16 %dest(register), [%adr(register)]
+01100001 dddd0000 0000aaaa 00000000
+# (31337_57200935026773, `Loads address %adr from main memory and stores it to %dest.`)
+
+load_16 %dest(register), [%adr:U16(immediate)]
+01110001 dddd0000 aaaaaaaa aaaaaaaa
+# (31337_57200935026773, `Loads address %adr from main memory and stores it to %dest.`)
+
+load_32 %dest(register), [%adr(register)]
+01100010 dddd0000 0000aaaa 00000000
+# (31337_57200935026773, `Loads address %adr from main memory and stores it to %dest.`)
+
+load_32 %dest(register), [%adr:U16(immediate)]
+01110010 dddd0000 aaaaaaaa aaaaaaaa
+# (31337_57200935026773, `Loads address %adr from main memory and stores it to %dest.`)
+
+pload %dest(register), [%adr(register)]
+01100011 dddd0000 0000aaaa 00000000
+# (31337_89257021109854, `Loads address %adr from persistent memory and stores it to %dest.`)
+
+pload %dest(register), [%adr:U16(immediate)]
+01110011 dddd0000 aaaaaaaa aaaaaaaa
+# (31337_89257021109854, `Loads address %adr from persistent memory and stores it to %dest.`)
+
+store_8 [%adr(register)], %value(register)
+01100100 0000vvvv 0000aaaa 00000000
+# (31337_61040780958703, `Stores %value to address %adr in main memory.`)
+
+store_8 [%adr:U16(immediate)], %value(register)
+01110100 0000vvvv aaaaaaaa aaaaaaaa
+# (31337_61040780958703, `Stores %value to address %adr in main memory.`)
+
+store_16 [%adr(register)], %value(register)
+01100101 0000vvvv 0000aaaa 00000000
+# (31337_61040780958703, `Stores %value to address %adr in main memory.`)
+
+store_16 [%adr:U16(immediate)], %value(register)
+01110101 0000vvvv aaaaaaaa aaaaaaaa
+# (31337_61040780958703, `Stores %value to address %adr in main memory.`)
+
+store_32 [%adr(register)], %value(register)
+01100110 0000vvvv 0000aaaa 00000000
+# (31337_61040780958703, `Stores %value to address %adr in main memory.`)
+
+store_32 [%adr:U16(immediate)], %value(register)
+01110110 0000vvvv aaaaaaaa aaaaaaaa
+# (31337_61040780958703, `Stores %value to address %adr in main memory.`)
+
+pstore [%adr(register)], %value(register)
+01100111 0000vvvv 0000aaaa 00000000
+# (31337_13110303123442, `Stores %value to address %adr in persistent memory.`)
+
+pstore [%adr:U16(immediate)], %value(register)
+01110111 0000vvvv aaaaaaaa aaaaaaaa
+# (31337_13110303123442, `Stores %value to address %adr in persistent memory.`)
+
+
+mov %a(register), %b(register)
+00100001 aaaa0000 0000bbbb 00000000
+# (31337_53941960758392, `Moves a value to %a from %b.`)
+
+mov %a(register), %b:U16(immediate | label)
+00110001 aaaa0000 bbbbbbbb bbbbbbbb
+# (31337_34859363394334, `Moves a value to %a.`)
+
+neg %a(register), %b(register)
+00100101 aaaa0000 0000bbbb 00000000
+# (31337_72894099288447, `Negates a %b and stores it in %a.`)
+
+neg %a(register), %b:U16(immediate | label)
+00110101 aaaa0000 bbbbbbbb bbbbbbbb
+# (31337_57504570243305, `Negates a value and stores it in %a.`)
+
+not %a(register), %b(register)
+00100011 aaaa0000 0000bbbb 00000000
+# (31337_55357258069734, `Toggles the bits of %b and stores it in %a.`)
+
+not %a(register), %b:U16(immediate | label)
+00110011 aaaa0000 bbbbbbbb bbbbbbbb
+# (31337_40508048121543, `Toggles the bits of a value and stores it in %a.`)
+
+
+push %a(register)
+00110101 11101110 00000000 00000100   01100110 0000aaaa 00001110 00000000
+# (31337_28545157055801, `Pushes %a onto the stack. This instruction is a synonym for:   sub sp, sp, 4   store_32 [sp], %a`)
+
+pop %a(register)
+01100010 aaaa0000 00001110 00000000   00110100 11101110 00000000 00000100
+# (31337_54469754973269, `Pops %a off the stack. This instruction is a synonym for:   load_32 %a, [sp]   add sp, sp, 4`)
+
+call %a(label)
+00000111 11110000 00000000 00000000   00110100 11111111 00000000 00010100   00110101 11101110 00000000 00000100   01100110 00001111 00001110 00000000   01011000 00001111 aaaaaaaa aaaaaaaa
+# (31337_57788320241950, `Calls %a. Overwrites the flag register. This instruction is a synonym for:   counter flags   add flags, flags, 20   sub sp, sp, 4   store_32 [sp], flags   jmp %a`)
+
+ret
+01100010 11110000 00001110 00000000   00110100 11101110 00000000 00000100   01001000 00001111 00001111 00000000
+# (31337_48332460366102, `Returns from the last function call. Overwrites the flag register. This instruction is a synonym for:   load_32 flags, [sp]   add sp, sp, 4   jmp flags`)
+

isa/test.isa

@@ -0,0 +1,361 @@
+[settings]
+name = "Symphony"
+
+[fields]
+
+register
+zr 0000
+r1 0001
+r2 0010
+r3 0011
+r4 0100
+r5 0101
+r6 0110
+r7 0111
+r8 1000
+r9 1001
+r10 1010
+r11 1011
+r12 1100
+r13 1101
+sp 1110
+flags 1111
+
+condition
+""     1000
+".all" 1000
+".e"   0001
+".ne"  1001
+".b"   0010
+".ae"  1010
+".be"  0011
+".a"   1011
+".l"   0100
+".ge"  1100
+".le"  0101
+".g"   1101
+
+[instructions]
+
+nop
+00000000 00000000 00000000 00000000
+# (31337_88272577071256, `Does nothing.`)
+
+in %a(register)
+00000001 aaaa0000 00000000 00000000
+# (31337_44524771082050, `Loads an input and stores it in %a.`)
+
+out %b(register)
+00000010 00000000 0000bbbb 00000000
+# (31337_18254089726214, `Sends %b to output.`)
+
+out %a:U16(immediate)
+00010010 00000000 aaaaaaaa aaaaaaaa
+# (31337_15915531259935, `Sends %a to output.`)
+
+keyboard %a(register)
+00000011 aaaa0000 00000000 00000000
+# (31337_27868418224252, `Loads keyboard input and stores it to %a.`)
+
+screen %a(register), %b(register)
+00000100 0000aaaa 0000bbbb 00000000
+# (31337_39857449355186, `Stores the value of %b in screen setting %a.`)
+
+screen %a(register), %b:U16(immediate)
+00010100 0000aaaa bbbbbbbb bbbbbbbb
+# (31337_12835125621741, `Stores the value of %b in screen setting %a.`)
+
+time_0 %a(register)
+00000101 aaaa0000 00000000 00000000
+# (31337_72551400437977, `Loads the lower four bytes of the time value and stores it to %a.`)
+
+time_1 %a(register)
+00000110 aaaa0000 00000000 00000000
+# (31337_68219187873304, `Loads the upper four bytes of the time value and stores it to %a.`)
+
+counter %a(register)
+00000111 aaaa0000 00000000 00000000
+# (31337_67376584796076, `Loads the counter value and stores it to %a.`)
+
+
+
+nand %a(register), %b(register), %c(register)
+00100000 aaaabbbb 0000cccc 00000000
+# (31337_86705346481666, `NAND %b and %c and stores the result in %a.`)
+
+or %a(register), %b(register), %c(register)
+00100001 aaaabbbb 0000cccc 00000000
+# (31337_40732211165530, `OR %b and %c and stores the result in %a.`)
+
+and %a(register), %b(register), %c(register)
+00100010 aaaabbbb 0000cccc 00000000
+# (31337_85679146831122, `AND %b and %c and stores the result in %a.`)
+
+nor %a(register), %b(register), %c(register)
+00100011 aaaabbbb 0000cccc 00000000
+# (31337_37333076617857, `NOR %b and %c and stores the result in %a.`)
+
+add %a(register), %b(register), %c(register)
+00100100 aaaabbbb 0000cccc 00000000
+# (31337_51030225266712, `ADD %b and %c and stores the result in %a.`)
+
+sub %a(register), %b(register), %c(register)
+00100101 aaaabbbb 0000cccc 00000000
+# (31337_28652904157569, `SUB %b and %c and stores the result in %a.`)
+
+xor %a(register), %b(register), %c(register)
+00100110 aaaabbbb 0000cccc 00000000
+# (31337_46967848572964, `XOR %b and %c and stores the result in %a.`)
+
+lsl %a(register), %b(register), %c(register)
+00100111 aaaabbbb 0000cccc 00000000
+# (31337_13576771671264, `Logical shifts left %b by %c and stores the result in %a.`)
+
+lsr %a(register), %b(register), %c(register)
+00101000 aaaabbbb 0000cccc 00000000
+# (31337_67019902294705, `Logical shifts right %b by %c and stores the result in %a.`)
+
+asr %a(register), %b(register), %c(register)
+00101001 aaaabbbb 0000cccc 00000000
+# (31337_42626144645228, `Arithmetic shift right %b by %c and stores the result in %a.`)
+
+cmp %a(register), %b(register)
+00101010 1111aaaa 0000bbbb 00000000
+# (31337_54565380946620, `Compares %a and %b and stores the result in the 'flags' register.`)
+
+
+nand %a(register), %b(register), %c:U16(immediate | label)
+00110000 aaaabbbb cccccccc cccccccc
+# (31337_75302656449127, `NAND %b and %c and stores the result in %a.`)
+
+or %a(register), %b(register), %c:U16(immediate | label)
+00110001 aaaabbbb cccccccc cccccccc
+# (31337_30574433901064, `OR %b and %c and stores the result in %a.`)
+
+nor %a(register), %b(register), %c:U16(immediate | label)
+00110011 aaaabbbb cccccccc cccccccc
+# (31337_46087142860391, `NOR %b and %c and stores the result in %a.`)
+
+and %a(register), %b(register), %c:U16(immediate | label)
+00110010 aaaabbbb cccccccc cccccccc
+# (31337_86713121915282, `AND %b and %c and stores the result in %a.`)
+
+add %a(register), %b(register), %c:U16(immediate | label)
+00110100 aaaabbbb cccccccc cccccccc
+# (31337_23349431010010, `ADD %b and %c and stores the result in %a.`)
+
+sub %a(register), %b(register), %c:U16(immediate | label)
+00110101 aaaabbbb cccccccc cccccccc
+# (31337_67495552371225, `SUB %b and %c and stores the result in %a.`)
+
+xor %a(register), %b(register), %c:U16(immediate | label)
+00110110 aaaabbbb cccccccc cccccccc
+# (31337_66785854415645, `XOR %b and %c and stores the result in %a.`)
+
+lsl %a(register), %b(register), %c:U16(immediate | label)
+00110111 aaaabbbb cccccccc cccccccc
+# (31337_54577249258785, `Logical shifts left %b by %c and stores the result in %a.`)
+
+lsr %a(register), %b(register), %c:U16(immediate | label)
+00111000 aaaabbbb cccccccc cccccccc
+# (31337_16685334571248, `Logical shifts right %b by %c and stores the result in %a.`)
+
+asr %a(register), %b(register), %c:U16(immediate | label)
+00111001 aaaabbbb cccccccc cccccccc
+# (31337_55551510150818, `Arithmetic shifts right %b and %c and stores the result in %a.`)
+
+cmp %a(register), %b:U16(immediate | label)
+00111010 1111aaaa bbbbbbbb bbbbbbbb
+# (31337_37102964808364, `Compares %a and %b and stores the result in the 'flags' register.`)
+
+
+jmp %a(register)
+01001000 00001111 0000aaaa 00000000
+# (31337_74148826866592, `Jumps to %a.`)
+
+
+jmp %a:U16(immediate | label)
+01011000 00001111 aaaaaaaa aaaaaaaa
+# (31337_90876214388280, `Jumps to %a.`)
+
+je %a:U16(immediate | label)
+01010001 00001111 aaaaaaaa aaaaaaaa
+# (31337_88180305667389, `Jumps to %a if the values were equal (reading results from 'flags').`)
+
+jne %a:U16(immediate | label)
+01011001 00001111 aaaaaaaa aaaaaaaa
+# (31337_67178948469318, `Jumps to %a if the values were not equal (reading results from 'flags').`)
+
+
+jb %a:U16(immediate | label)
+01010010 00001111 aaaaaaaa aaaaaaaa
+# (31337_31763492459833, `Jumps to %a if the first value was below (unsigned) the second (reading results from 'flags').`)
+
+jae %a:U16(immediate | label)
+01011010 00001111 aaaaaaaa aaaaaaaa
+# (31337_82087388048746, `Jumps to %a if the first value was above (unsigned) or equal to the second (reading results from 'flags').`)
+
+jbe %a:U16(immediate | label)
+01010011 00001111 aaaaaaaa aaaaaaaa
+# (31337_26183125927881, `Jumps to %a if the First value was below (unsigned) or equal to the second (reading results from 'flags').`)
+
+ja %a:U16(immediate | label)
+01011011 00001111 aaaaaaaa aaaaaaaa
+# (31337_11626177279992, `Jumps to %a if the first value was above (unsigned) the second (reading results from 'flags').`)
+
+
+jl %a:U16(immediate | label)
+01010100 00001111 aaaaaaaa aaaaaaaa
+# (31337_71637103729391, `Jumps to %a if the first value was less (signed) than the second (reading results from 'flags').`)
+
+jge %a:U16(immediate | label)
+01011100 00001111 aaaaaaaa aaaaaaaa
+# (31337_53499765587663, `Jumps to %a if the first value was greater (signed) or equal to the second (reading results from 'flags').`)
+
+jle %a:U16(immediate | label)
+01010101 00001111 aaaaaaaa aaaaaaaa
+# (31337_77040234358389, `Jumps to %a if the first value was less (signed) or equal to the second (reading results from 'flags').`)
+
+jg %a:U16(immediate | label)
+01011101 00001111 aaaaaaaa aaaaaaaa
+# (31337_71317192057126, `Jumps to %a if the first value was greater (signed) than the second (reading results from 'flags').`)
+
+
+
+load_8 %dest(register), [%adr(register)]
+01100000 dddd0000 0000aaaa 00000000
+# (31337_57200935026773, `Loads address %adr from main memory and stores it to %dest.`)
+
+load_8 %dest(register), [%adr:U16(immediate | label)]
+01110000 dddd0000 aaaaaaaa aaaaaaaa
+# (31337_57200935026773, `Loads address %adr from main memory and stores it to %dest.`)
+
+load_16 %dest(register), [%adr(register)]
+01100001 dddd0000 0000aaaa 00000000
+# (31337_57200935026773, `Loads address %adr from main memory and stores it to %dest.`)
+
+load_16 %dest(register), [%adr:U16(immediate | label)]
+01110001 dddd0000 aaaaaaaa aaaaaaaa
+# (31337_57200935026773, `Loads address %adr from main memory and stores it to %dest.`)
+
+load_32 %dest(register), [%adr(register)]
+01100010 dddd0000 0000aaaa 00000000
+# (31337_57200935026773, `Loads address %adr from main memory and stores it to %dest.`)
+
+load_32 %dest(register), [%adr:U16(immediate | label)]
+01110010 dddd0000 aaaaaaaa aaaaaaaa
+# (31337_57200935026773, `Loads address %adr from main memory and stores it to %dest.`)
+
+pload %dest(register), [%adr(register)]
+01100011 dddd0000 0000aaaa 00000000
+# (31337_89257021109854, `Loads address %adr from persistent memory and stores it to %dest.`)
+
+pload %dest(register), [%adr:U16(immediate)]
+01110011 dddd0000 aaaaaaaa aaaaaaaa
+# (31337_89257021109854, `Loads address %adr from persistent memory and stores it to %dest.`)
+
+store_8 [%adr(register)], %value(register)
+01100100 0000vvvv 0000aaaa 00000000
+# (31337_61040780958703, `Stores %value to address %adr in main memory.`)
+
+store_8 [%adr:U16(immediate | label)], %value(register)
+01110100 0000vvvv aaaaaaaa aaaaaaaa
+# (31337_61040780958703, `Stores %value to address %adr in main memory.`)
+
+store_16 [%adr(register)], %value(register)
+01100101 0000vvvv 0000aaaa 00000000
+# (31337_61040780958703, `Stores %value to address %adr in main memory.`)
+
+store_16 [%adr:U16(immediate | label)], %value(register)
+01110101 0000vvvv aaaaaaaa aaaaaaaa
+# (31337_61040780958703, `Stores %value to address %adr in main memory.`)
+
+store_32 [%adr(register)], %value(register)
+01100110 0000vvvv 0000aaaa 00000000
+# (31337_61040780958703, `Stores %value to address %adr in main memory.`)
+
+store_32 [%adr:U16(immediate | label)], %value(register)
+01110110 0000vvvv aaaaaaaa aaaaaaaa
+# (31337_61040780958703, `Stores %value to address %adr in main memory.`)
+
+pstore [%adr(register)], %value(register)
+01100111 0000vvvv 0000aaaa 00000000
+# (31337_13110303123442, `Stores %value to address %adr in persistent memory.`)
+
+pstore [%adr:U16(immediate)], %value(register)
+01110111 0000vvvv aaaaaaaa aaaaaaaa
+# (31337_13110303123442, `Stores %value to address %adr in persistent memory.`)
+
+
+mov %a(register), %b(register)
+00100001 aaaa0000 0000bbbb 00000000
+# (31337_53941960758392, `Moves a value to %a from %b.`)
+
+mov %a(register), %b:U16(immediate | label)
+00110001 aaaa0000 bbbbbbbb bbbbbbbb
+# (31337_34859363394334, `Moves a value to %a.`)
+
+neg %a(register), %b(register)
+00100101 aaaa0000 0000bbbb 00000000
+# (31337_72894099288447, `Negates a %b and stores it in %a.`)
+
+neg %a(register), %b:U16(immediate | label)
+00110101 aaaa0000 bbbbbbbb bbbbbbbb
+# (31337_57504570243305, `Negates a value and stores it in %a.`)
+
+not %a(register), %b(register)
+00100011 aaaa0000 0000bbbb 00000000
+# (31337_55357258069734, `Toggles the bits of %b and stores it in %a.`)
+
+not %a(register), %b:U16(immediate | label)
+00110011 aaaa0000 bbbbbbbb bbbbbbbb
+# (31337_40508048121543, `Toggles the bits of a value and stores it in %a.`)
+
+
+push %a(register)
+00110101 11101110 00000000 00000100   01100110 0000aaaa 00001110 00000000
+# (31337_28545157055801, `Pushes %a onto the stack. This instruction is a synonym for:   sub sp, sp, 4   store_32 [sp], %a`)
+
+pop %a(register)
+01100010 aaaa0000 00001110 00000000   00110100 11101110 00000000 00000100
+# (31337_54469754973269, `Pops %a off the stack. This instruction is a synonym for:   load_32 %a, [sp]   add sp, sp, 4`)
+
+call %a(label)
+00000111 11110000 00000000 00000000   00110100 11111111 00000000 00010100   00110101 11101110 00000000 00000100   01100110 00001111 00001110 00000000   01011000 00001111 aaaaaaaa aaaaaaaa
+# (31337_57788320241950, `Calls %a. Overwrites the flag register. This instruction is a synonym for:   counter flags   add flags, flags, 20   sub sp, sp, 4   store_32 [sp], flags   jmp %a`)
+
+ret
+01100010 11110000 00001110 00000000   00110100 11101110 00000000 00000100   01001000 00001111 00001111 00000000
+# (31337_48332460366102, `Returns from the last function call. Overwrites the flag register. This instruction is a synonym for:   load_32 flags, [sp]   add sp, sp, 4   jmp flags`)
+
+
+li %r(register), %a:S33(immediate | label)
+; assert(0 - 0x80000000 <= %a, "%a is too low")
+; assert(%a <= 0xffffffff, "%a is too high")
+%s = trailing_zeros(%a)
+%sa = %a >> %s
+%nota = %a ^ 0xffffffff
+when %a <=u 0xffff   : 00110001 %r[3:0]0000 %a[15:0]                                                 ; First 64k
+when %nota <=u 0xffff: 00110001 %r[3:0]0000 %nota[15:0]    00100011 %r[3:0]0000 0000%r[3:0] 00000000 ; Last 64k
+when %sa <=u 0xffff  : 00110001 %r[3:0]0000 %sa[15:0]      00110111 %r[3:0]%r[3:0] 00000000 %s[7:0]  ; Aligned
+00110001 %r[3:0]0000 %a[31:16]   00110111 %r[3:0]%r[3:0] 00000000 00010000   00110001 %r[3:0]%r[3:0] %a[15:0]          ; Any 32-bit
+# Load 32-bit immediate %a into %r
+
+qcall %a:U32(label)
+; assert(0 - 0x80000000 <= %a, "%a is too low")
+; assert(%a <= 0xffffffff, "%a is too high")
+%r = 13
+%f = 15
+%s = trailing_zeros(%a)
+%sa = %a >> %s
+%nota = %a ^ 0xffffffff
+when %a <=u 0xffff   : 01011000 %r[3:0]ffff %a[15:0]                                                                                              ; First 64k
+when %nota <=u 0xffff: 00110001 %r[3:0]0000 %nota[15:0]    00100011 %r[3:0]0000 0000%r[3:0] 00000000    01001000 %r[3:0]ffff 0000%r[3:0] 00000000 ; Last 64k
+when %sa <=u 0xffff  : 00110001 %r[3:0]0000 %sa[15:0]      00110111 %r[3:0]%r[3:0] 00000000 %s[7:0]     01001000 %r[3:0]ffff 0000%r[3:0] 00000000 ; Aligned
+00110001 %r[3:0]0000 %a[31:16]   00110111 %r[3:0]%r[3:0] 00000000 00010000   00110001 %r[3:0]%r[3:0] %a[15:0]    01001000 %r[3:0]ffff 0000%r[3:0] 00000000 ; Any 32-bit
+# Jump and link to 32-bit label
+
+halt%c(condition)
+1000cccc 00001111 00000000 00000000
+# Halt on condition %c
+

src/LUTs.asm

@@ -0,0 +1,100 @@
+@0x10000 ; Example address until we get a proper memory map for this
+
+; Shift conversion table
+; It stores the mapping from value 32-127 of the ASCII table to their shifted equivalents (both ways) in the standard US keyboard layout
+; e.g. 1 -> !
+U8 32 ; Space -> Space
+U8 49 ; ! -> 1
+U8 39 ; " -> '
+U8 51 ; # -> 3
+U8 52 ; $ -> 4
+U8 53 ; % -> 5
+U8 55 ; & -> 7
+U8 34 ; ' -> "
+U8 57 ; ( -> 9
+U8 48 ; ) -> 0
+U8 56 ; * -> 8
+U8 61 ; + -> =
+U8 60 ; , -> <
+U8 95 ; - -> _
+U8 62 ; . -> >
+U8 63 ; / -> ?
+U8 41 ; 0 -> )
+U8 33 ; 1 -> !
+U8 64 ; 2 -> @
+U8 35 ; 3 -> #
+U8 36 ; 4 -> $
+U8 37 ; 5 -> %
+U8 94 ; 6 -> ^
+U8 38 ; 7 -> &
+U8 42 ; 8 -> *
+U8 40 ; 9 -> (
+U8 59 ; : -> ;
+U8 58 ; ; -> :
+U8 44 ; < -> ,
+U8 43 ; = -> +
+U8 46 ; > -> .
+U8 47 ; ? -> /
+U8 50 ; @ -> 2
+U8 97 ; A -> a
+U8 98 ; B -> b
+U8 99 ; C -> c
+U8 100; D -> d
+U8 101; E -> e
+U8 102; F -> f
+U8 103; G -> g
+U8 104; H -> h
+U8 105; I -> i
+U8 106; J -> j
+U8 107; K -> k
+U8 108; L -> l
+U8 109; M -> m
+U8 110; N -> n
+U8 111; O -> o
+U8 112; P -> p
+U8 113; Q -> q
+U8 114; R -> r
+U8 115; S -> s
+U8 116; T -> t
+U8 117; U -> u
+U8 118; V -> v
+U8 119; W -> w
+U8 120; X -> x
+U8 121; Y -> y
+U8 122; Z -> z
+U8 123; [ -> {
+U8 124; \ -> |
+U8 125; ] -> }
+U8 125; ^ -> 6
+U8 45 ; _ -> -
+U8 126; ` -> ~
+U8 65 ; a -> A
+U8 66 ; b -> B
+U8 67 ; c -> C
+U8 68 ; d -> D
+U8 69 ; e -> E
+U8 70 ; f -> F
+U8 71 ; g -> G
+U8 72 ; h -> H
+U8 73 ; i -> I
+U8 74 ; j -> J
+U8 75 ; k -> K
+U8 76 ; l -> L
+U8 77 ; m -> M
+U8 78 ; n -> N
+U8 79 ; o -> O
+U8 80 ; p -> P
+U8 81 ; q -> Q
+U8 82 ; r -> R
+U8 83 ; s -> S
+U8 84 ; t -> T
+U8 85 ; u -> U
+U8 86 ; v -> V
+U8 87 ; w -> W
+U8 88 ; x -> X
+U8 89 ; y -> Y
+U8 90 ; z -> Z
+U8 91 ; { -> [
+U8 92 ; | -> \
+U8 93 ; } -> ]
+U8 96 ; ~ -> `

src/array.asm

@@ -0,0 +1,77 @@
+; Returns the index of the first element matching the provided predicate function (or -1 if not found)
+; Arguments:
+; r1 - The array pointer
+; r2 - The array length (number of items)
+; r3 - The stride (size of one item) - either 1, 2 or 4 (bytes)
+; r4 - The predicate
+; r5 - Predicate context
+; Result:
+; r1 - The index of the first element matching the provided predicate function (or -1 if not found)
+; Clobbers: r2, r3, r4, r5, r6, + what the predicate clobbers
+; Info:
+; The predicate function should follow the stdlib calling convention
+; The predicate receives two arguments (the value and the predicate context) and should return either a zero when the value is not the one we search for
+; , or any other result if it is the searched-for item.
+pub find_index:
+    push r12 ; We will store the predicate pointer here
+    push r11 ; We will store the current pointer here
+    push r10 ; We will store the stride here
+    push r9 ; We will store the final address here
+    push r8 ; We will store the mask here
+
+    mov r12, r4
+    mov r11, r1
+    mov r10, r3
+    mov r9, r2
+    lsr r6, r3, 1 ; We turn the stride into a byte shift
+    lsl r9, r9, r6 ; We calculate bytes left
+    add r9, r9, r1 ; We add the start address to get the final address
+
+    push r13 ; We save up the return address because we will provide our own to the predicate
+    push r1 ; We need the array pointer to calculate the item index
+    counter r13
+    add r13, r13, 52 ; Point to just after the predicate call - we can set this up now so we don't waste loop cycles
+
+    nand r8, zr, zr ; We create a mask of 0xFFFFFFFF
+    mov r6, 4
+    sub r6, r6, r3 ; We create a "negative stride", e.g. 4 -> 0, 2 -> 2, 1 -> 3
+    lsl r6, r6, 3
+    lsr r8, r8, r6 ; We shift the mask by the negative stride to obtain the proper mask for a value
+    ; e.g. stride 4 -> mask is 0xFFFFFFFF
+    ; stride 2 -> mask is 0x0000FFFF
+    ; stride 1 -> mask is 0x000000FF
+
+    push r5 ; We save the predicate context on the stack
+    find_index_loop:
+        load_32 r1, [r11] ; We load the element
+        and r1, r1, r8 ; We mask it to handle stride 2 and 1 cases
+        load_32 r2, [sp] ; We load the predicate context into r2
+        jmp r12 ; We call the predicate
+        cmp r1, zr
+        jne find_index_found_item ; If we found the item, we jump out
+        ; If we didn't, move to next item
+        add r11, r11, r10 ; We add the stride to the pointer
+        cmp r11, r9 ; We compare with the final address
+        jne find_index_loop ; If we did not reach the end we jump back into the loop
+    
+    find_index_not_found:
+        add sp, sp, 8 ; The predicate context and old array pointer are not useful
+        pop r13 ; We get our return address
+        nand r1, zr, zr ; We put -1 in r1
+        jmp find_index_postamble
+    
+    find_index_found_item:
+        add sp, sp, 4 ; The predicate context is not useful
+        pop r1 ; We get the array pointer
+        pop r13 ; We get our return address
+        sub r1, r11, r1 ; We calculate the bytes from the start
+        lsr r10, r10, 1 ; We shift the stride to get the amount to shift the bytes for
+        lsr r1, r1, r10 ; We shift to get the index of the item
+
+    find_index_postamble:
+        pop r8
+        pop r9
+        pop r10
+        pop r11
+        pop r12
+        jmp r13 ; Return

src/console.asm

@@ -0,0 +1,69 @@
+; Reads a line from the keyboard and fills the specified buffer with it
+; Does not support Shift or any other special keys
+; Arguments:
+; r1 - pointer to the buffer
+; Result:
+; r1 - pointer to the same buffer
+; Clobbers: r2, r3, r4, r5, r6, r7
+pub read_line:
+	mov r6, 1
+	lsl r6, r6, 16
+	sub r6, r6, 32 ; Calculating the address to the shift LUT
+	mov r2, 0 ; Storing the shift status here
+	mov r4, 0 ; Storing the last key here, so we don't repeat the same key
+	mov r3, r1 ; The pointer to after the last character
+
+	read_line_keyloop:
+		keyboard r5
+		
+		cmp r5, r4
+		je read_line_keyloop ; If the current key is same as previous, we loop
+		mov r4, r5 ; Storing current key as previous
+		
+		cmp r5, 0x120 ; Is the key renderable or special?
+		jb read_line_special ; If the key was special, we handle it separately
+		xor r5, r5, 0x100 ; Clearing the "down" bit
+
+		cmp r2, zr ; Checking for shift status
+		je read_line_store ; If shift is up, we skip conversion
+
+		;;; converting from shift-down to shift-up keys
+		add r7, r6, r5 ; Calculating the index of the shift conversion
+		load_8 r5, [r7] ; Loading the shifted value
+		;;;
+
+		read_line_store:
+			store_8 [r3], r5 ; Else, we store the key in the buffer
+			add r3, r3, 1 ; We advance forward
+			; TODO: Writeback
+			jmp read_line_keyloop
+
+		read_line_special:
+			cmp r5, 13 ; Was the key Backspace?
+			je read_line_backspace ; If yes we need to move one character back
+
+			cmp r5, 10 ; Was the key Enter?
+			je read_line_finished ; If so, we're finished
+
+			and r5, r5, 0x1FB ; Mask out the left/right shift direction bit
+			cmp r5, 0x110 ; Was the key Shift Down?
+			and flags, flags, 0x1 ; We care only about equality bit
+			or r2, r2, flags ; If shift was down before, it still is. If it was pressed now, it is down now
+
+			cmp r5, 0x010 ; Was the key Shift Up?
+			and flags, flags, 0x1 ; We care only about equality bit
+			xor flags, flags, 0x1 ; We invert it, i.e. "if it's not up"
+			and r2, r2, flags ; The shift can be kept down if it's not currently up
+
+			jmp read_line_keyloop ; If no special handling, we loop back
+
+		read_line_backspace:
+			cmp r3, r1 ; Compare the current pointer to start of buffer
+			je read_line_keyloop ; If we are at the start, we loop
+			sub r3, r3, 1 ; We move back one character
+			; TODO: Writeback
+			jmp read_line_keyloop
+
+	read_line_finished:
+		store_8 [r3], zr ; We store null at the end so the string is finished
+		jmp r13

src/errno.asm

@@ -0,0 +1,30 @@
+; Error numbers should be 16 bit ODD numbers, so they can be loaded as immediates
+; and can be checked with:
+;
+;   qcall falible_function
+;   jne falible_ok ; Jump no error
+;       ; handle error
+;   falible_ok:
+;   ; Happy path
+;   ; ...
+; OR
+;   qcall falible_function
+;   je handle_error ; Jump if error
+;   ; Happy path
+;   ; ...
+;   handle_error:
+;       ; handle error
+
+pub const OK                   = 0x0000
+pub const SCREEN_INVALID_MODE  = 0x0001
+pub const SCREEN_INVALID_WIDTH = 0x0003
+pub const SCREEN_FB_TOO_SMALL  = 0x0005
+pub const SCREEN_OUTSIDE_FB    = 0x0007
+
+pub const INTTOSTR_BAD_BASE    = 0x0101
+pub const INTTOSTR_BAD_BUFFER  = 0x0103
+
+pub const MAGIC_BAD            = 0x8001
+
+; Extended error codes, these would require loading a 32 bit value.
+pub const EXT_OK              = 0x00000000

src/globals.asm

@@ -0,0 +1,30 @@
+; Addresses of global variables
+
+pub const MAGIC_ADDRESS_LONG = 0x0c       ; U32 Location of the magic value
+pub const MAGIC_VALUE_LONG   = 0xb301534c ; U32 Full 32 bits of the magic value
+pub const MAGIC_ADDRESS      = 0x0e       ; U16 Location of the low 16 bits of magic value
+pub const MAGIC_VALUE        = 0x534c     ; U16 Low 16 bits of the magic value
+
+; If not double buffering these point to the same buffer
+; If double buffering they must the same size
+pub const FB_DISPLAY_PTR     = 0x10       ; U32 Currently displayed buffer
+pub const FB_DISPLAY_STRIDE  = 0x14       ; U16 Bytes in each row of the displayed buffer
+pub const FB_DISPLAY_DEPTH   = 0x16       ; U16 Bits per pixel of the display buffer
+pub const FB_DRAW_PTR        = 0x18       ; U32 Draw to this buffer
+pub const FB_DRAW_STRIDE     = 0x1c       ; U16 Bytes in each row of the draw buffer == FB_DISPLAY_STRIDE
+pub const FB_DRAW_DEPTH      = 0x1e       ; U16 Bits per pixel of the draw buffer == FB_DISPLAY_DEPTH
+pub const FB_SIZE_BYTE       = 0x20       ; U32 In bytes
+pub const FB_WIDTH_PX        = 0x24       ; U16 Width of screen in pixels
+pub const FB_HEIGHT_PX       = 0x26       ; U16 Height of screen in pixels
+
+; Log2 of width in pixels, e.g.
+; * 10 => 1024 * 768
+; *  8 =>  256 * 192
+pub const FB_LOG_WIDTH       = 0x28       ; U8
+pub const FB_LOG_STRIDE      = 0x29       ; U8 Log2 of FB_xxx_STRIDE in bytes
+
+pub const FB_BYTES_PER_PIXEL = 0x2a       ; U8 Specialisations should hardcode this
+; Log2 of bytes per pixel
+; * 0 => 8 bits per pixel
+; * 2 => 32 bits per pixel
+pub const FB_LOG_BPP         = 0x2b       ; U8 Specialisations should hardcode this

src/imath.asm

@@ -4,22 +4,53 @@
 ; r2 - The second value
 ; Result:
 ; r1 - The lower 32 bits of the result
-; Clobbers: r2, r3, r4, r5
+; Clobbers: r2, r3, r4, r5, r6
 pub mul_low:
-	mov r3, 0 ; result
+	cmp r1, r2
-	mov r4, 31 ; loop counter
+	jbe mul_low_noswap
-	
+	xor r1, r2, r1
-	mul_low_loop:
+	xor r2, r1, r2
-		asr r5, r2, 31
+	xor r1, r2, r1
-		and r5, r5, r1
+	; Passthrough
-		lsl r5, r5, r4
+
-		add r3, r3, r5
+; Multiplies r1 and r2, returning the lower part of the result
-		lsl r2, r2, 1
+; This method assumes r1 is smaller than r2, which results in faster execution
-		sub r4, r4, 1
+; Arguments:
-		cmp r4, 0
+; r1 - The first value
-		jge mul_low_loop
+; r2 - The second value
-	mov r1, r3
+; Result:
+; r1 - The lower 32 bits of the result
+; Clobbers: r2, r3, r4, r5, r6
+pub mul_low_noswap:
+	mov r4, 0 ; r4 has the result
+	mov r6, mul_loop_end
+	add r3, r2, r2
 	
+	mul_loop:
+		and r5, r1, 14 ; Taking the first four bits, discarding the odd
+		lsl r5, r5, 1 ; 0000 - 0, 0001 - 2, 0010 - 4, 0011 - 8, etc.
+		sub r5, r6, r5
+		jmp r5
+		
+		add r4, r4, r3
+		add r4, r4, r3
+		add r4, r4, r3
+		add r4, r4, r3
+		add r4, r4, r3
+		add r4, r4, r3
+		add r4, r4, r3
+		mul_loop_end:
+			mov flags, r1
+			jne mul_skip_one
+			add r4, r4, r2
+			mul_skip_one:
+			lsl r2, r2, 4
+			lsl r3, r3, 4
+			lsr r1, r1, 4
+			cmp r1, zr
+			jne mul_loop
+
+	mov r1, r4
 	jmp r13
 
 ; Calculates the absolute value of the value provided in the r1 register

src/int_to_string.asm

@@ -0,0 +1,239 @@
+include errno
+
+; Convert integer to string
+; Arguments:
+; r1 - Integer
+; r2 - Start of buffer
+; r3 - Buffer length
+; r4 - Base (2, 8, 10, or 16)
+; Result:
+; none
+; Clobbers:
+; Based on specialization
+pub auto:
+cmp r4, 2
+je bin
+cmp r4, 8
+je oct
+cmp r4, 16
+je hex
+cmp r4, 10
+jmp dec
+mov flags, errno.INTTOSTR_BAD_BASE
+jmp r13
+
+; The output buffer is too small for this integer
+badbuffer:
+mov flags, errno.INTTOSTR_BAD_BUFFER
+jmp r13
+
+; All digits have been output. Null terminate and exit.
+done:
+store_8 [r2], zr
+mov flags, errno.OK
+jmp r13
+
+; Convert integer to binary string
+; Arguments:
+; r1 - Integer
+; r2 - Start of buffer
+; r3 - Buffer length
+; Result:
+; none
+; Clobbers:
+; flags
+; r4 - counter
+; r5 - character
+pub bin:
+mov r4, 31
+cmp r2, 2
+jl badbuffer
+
+bin_find_one:
+lsr r5, r1, r4          ; Select bit and advance counter
+and r5, r5, 1
+sub r4, r4, 1
+
+cmp r4, zr              ; Start printing if last bit ...
+jl bin_print
+cmp r5, zr              ; .. or if nonzero
+je bin_find_one
+
+add flags, r4, 3        ; Check buffer size
+cmp flags, r3
+ja badbuffer
+
+bin_print:
+add r5, r5, 0x30 ; '0'  ; Add digit to buffer
+store_8 [r2], r5
+add r2, r2, 1
+cmp r4, zr              ; Done if last bit
+jl done
+lsr r5, r1, r4          ; Select bit and advance counter
+and r5, r5, 1
+sub r4, r4, 1
+jmp bin_print
+
+; Convert integer to octal string
+; Arguments:
+; r1 - Integer
+; r2 - Start of buffer
+; r3 - Buffer length
+; Result:
+; none
+; Clobbers:
+; flags
+; r4 - input counter
+; r5 - character
+; r6 - output size counter
+pub oct:
+mov r4, 30
+mov r6, 12
+
+oct_find_one:
+lsr r5, r1, r4          ; Select bit and advance counter
+and r5, r5, 7
+sub r4, r4, 3
+sub r6, r6, 1
+
+cmp r4, zr              ; Start printing if last bit ...
+jl oct_print
+cmp r5, zr              ; .. or if nonzero
+je oct_find_one
+
+cmp r6, r3              ; Check buffer size
+ja badbuffer
+
+oct_print:
+add r5, r5, 0x30 ; '0'  ; Add digit to buffer
+store_8 [r2], r5
+add r2, r2, 1
+cmp r4, zr              ; Done if last bit
+jl done
+lsr r5, r1, r4          ; Select bit and advance counter
+and r5, r5, 7
+sub r4, r4, 3
+jmp oct_print
+
+; Convert integer to hexadecimal string
+; Arguments:
+; r1 - Integer
+; r2 - Start of buffer
+; r3 - Buffer length
+; Result:
+; none
+; Clobbers:
+; flags
+; r4 - input counter
+; r5 - character
+pub hex:
+mov r4, 28
+
+hex_find_one:
+lsr r5, r1, r4          ; Select bit and advance counter
+and r5, r5, 0xF
+sub r4, r4, 4
+
+cmp r4, zr              ; Start printing if last bit ...
+jl hex_print
+cmp r5, zr              ; .. or if nonzero
+je hex_find_one
+
+lsr flags, r5, 2        ; Check buffer size
+add flags, flags, 3
+cmp flags, r3
+ja badbuffer
+
+hex_print:
+add r5, r5, 0x30 ; '0'  ; Add digit to buffer
+cmp r5, 0x39 ; '9'
+jle hex_no_letter
+add r5, r5, 0x07 ; 'A' - '0' - 10
+hex_no_letter:
+store_8 [r2], r5
+add r2, r2, 1
+cmp r4, zr              ; Done if last bit
+jl done
+lsr r5, r1, r4          ; Select bit and advance counter
+and r5, r5, 0xF
+sub r4, r4, 4
+jmp hex_print
+
+; Convert integer to decimal string
+; Arguments:
+; r1 - Integer
+; r2 - Start of buffer
+; r3 - Buffer length
+; Result:
+; none
+; Clobbers:
+; flags
+; r4, r5
+pub dec:
+mov r4, 0x5F5
+lsl r4, r4, 16
+add r4, r4, 0xE100 ; 100 million; 8 digits
+cmp r1, r4
+jl dec_small
+; TODO large
+
+
+; Small numbers have at least most 8 digits, thus their BCD form fits in
+; one register. Bit 26 is the highest which can be set.
+;
+; Utilizes double dabble
+; r4, r5 are loop counters
+;
+; for( r4 = 24 ; r4 > 0 ; r4-- )
+;   for( r5 = r4 ; r5 <= 28 ; r5+= 4 )
+;     if( ((r1 >> r5) & 0xF) >= 5 )
+;       r1 += 3 << r5
+dec_small:
+mov r4, 24
+dec_small_dabble_outer:
+mov r5, r4
+dec_small_dabble_inner:
+lsr flags, r1, r5
+and flags, flags, 0xF
+cmp flags, 5
+jl dec_small_dabble_noinc
+mov flags, 3
+lsl flags, flags, r5
+add r1, r1, flags
+dec_small_dabble_noinc:
+add r5, r5, 4
+cmp r5, 28
+jle dec_small_dabble_inner
+sub r4, r4, 1
+cmp r4, zr
+jg dec_small_dabble_outer
+
+; Print the BCD in r1
+; r4 is a counter
+; r5 is the output character
+mov r4, 28
+dec_find_one:
+lsr r5, r1, r4          ; Select bit and advance counter
+and r5, r5, 0xF
+sub r4, r4, 4
+
+cmp r4, zr               ; Start printing if last bit ...
+jl dec_print
+cmp r5, zr              ; .. or if nonzero
+je dec_find_one
+
+lsr flags, r5, 2        ; Check buffer size
+add flags, flags, 3
+cmp flags, r3
+ja badbuffer
+
+dec_print:
+add r5, r5, 0x30 ; '0'  ; Add digit to buffer
+store_8 [r2], r5
+add r2, r2, 1
+cmp r4, zr              ; Done if last bit
+jl done
+lsr r5, r1, r4          ; Select bit and advance counter
+and r5, r5, 0xF
+sub r4, r4, 4
+jmp dec_print

src/mem.asm

@@ -0,0 +1,174 @@
+; int compare(uint8_t* a, uint8_t* b, size_t count);
+;   Compares two memory segment of equal length lexicographically.
+;
+; Arguments:
+; - `r1`: A pointer to the first memory segment.
+; - `r2`: A pointer to the second memory segment.
+; - `r3`: The size of both memory segments.
+; Results:
+; - `r1`:
+;   -  `0` if both segments are equal.
+;   - `<0` if the first segment is less than the second segment.
+;   - `>0` if the first segment is greater than the second segment.
+;
+pub compare:
+    ; Exclusive end point of the first segment.
+    add r3, r3, r1
+    sub r3, r3, 4
+_compare__loop:
+    load_32 r4, [r1]
+    add r1, r1, 4
+    load_32 r5, [r2]
+    add r2, r2, 4
+    ; Comparing two sequences of 4 bytes lexicographically is equivalent to
+    ; comparing the corresponding big endian 32 bit words.
+    cmp r4, r5
+    jne _compare__break
+    ; Check if there are enough bytes left to continue with the vectorized loop.
+    cmp r1, r3
+    jbe _compare__loop
+    ; `r3 + 4 - r1 = <remaining byte count> = r3 - r1 mod 4`
+    sub flags, r3, r1
+    ; Check if one of the lowest 2 bits is non-zero
+    jbe _compare__rem
+    ; If not, we are done. Both segments are equal.
+    mov r1, 0
+    jmp r13
+_compare__break:
+    ; `flags` is the comparison result in the format of `cmp`. Convert it to the desired format.
+    ; 00 => 0x40000000 > 0
+    ; 01 => 0x00000000 = 0
+    ; 10 => 0xC0000000 < 0
+    xor r1, flags, 1
+    lsl r1, r1, 30
+    jmp r13
+_compare__rem:
+    ; Compute `S = 8*(4 - <remaining byte count>)` and
+    ; [r1] >> S, [r2] >> S
+    mov r3, 8
+    load_32 r4, [r1]
+    sub r3, r3, flags
+    load_32 r5, [r2]
+    lsl r3, r3, 3
+    lsr r4, r4, r3
+    lsr r5, r5, r3
+    ; Compare both values, now with garbage bytes removed.
+    cmp r4, r5
+    jmp _compare__break
+
+
+; void copy(void* src, void* dest, size_t count);
+;   Copies `count` bytes from `src` to `dest`. The two memory segments must not overlap.
+;
+; Arguments:
+; - `r1`: Pointer to the memory segment to be copied.
+; - `r2`: Pointer to the memory segment to be copied into.
+; - `r3`: Byte size of both the `src` and `dest` segments.
+;
+pub copy:
+    ; Exclusive end point of the source segment.
+    add r3, r1, r3
+    ; Last index from where we can safely copy 8 bytes per loop iteration.
+    sub r3, r3, 8
+    jmp _copy__loop_entry
+_copy__loop:
+    ; Copy 8 bytes from `src` to `dest`.
+    load_32 flags, [r1]
+    add r1, r1, 4
+    store_32 [r2], flags
+    add r2, r2, 4
+    load_32 flags, [r1]
+    add r1, r1, 4
+    store_32 [r2], flags
+    add r2, r2, 4
+_copy__loop_entry:
+    ; Check if we can process more data in the vectorized loop.
+    cmp r1, r3
+    jbe _copy__loop
+    ; The remaining amount of bytes `R` is `R = r3 + 8 - r1 = r3 - r1 mod 8`.
+    sub flags, r3, r1
+    ; Test if `R` is not a multiple of `4`, i.e. the lowest 2 bits are non-zero.
+    jbe _copy__rem
+    ; `R` is a multiple of `4`. Special case this.
+    ; Check if `R` is `0`, i.e. the third bit is also 0. In that case, we are already done.
+    ; There are no conditional indirect jumps, so we can't return immediately.
+    jge _copy__ret
+    ; `R = 4`. No need to update `r1` or `r2`, we don't need them anymore.
+    load_32 flags, [r1]
+    store_32 [r2], flags
+_copy__ret:
+    ; Return
+    jmp r13
+_copy__rem:
+    ; Optimize the remaining cases for code size.
+    ; End point of the source segment.
+    add r3, r3, 8
+    ; We already handled the case `R = 0` earlier,
+    ; so no bounds check needed for the first iteration.
+_copy__rem_loop:
+    ; Copy 1 byte.
+    load_8 flags, [r1]
+    add r1, r1, 1
+    store_8 [r2], flags
+    add r2, r2, 1
+    ; Check if we are still within the bounds.
+    cmp r1, r3
+    jb _copy__rem_loop
+    jmp r13
+    
+; void fill32(uint8_t* dest, size_t count, uint32_t value);
+;   Fills `count` bytes in `dest` with `value`. If `count` is not a multiple of 4, 
+;   the least significant bytes of `value` are cut off for the last entry.
+;
+; Arguments:
+; - `r1`: A pointer to the destination segment.
+; - `r2`: The size of the destination segment.
+; - `r3`: The 32 bit value that the segment is filled with.
+;
+pub fill32:
+    ; Exclusive end point of the destination segment.
+    add r2, r1, r2
+    ; Last index from where we can safely write 8 bytes per loop iteration.
+    sub r2, r2, 8
+    jmp _fill32__entry
+_fill32__loop:
+	; Set 8 bytes per loop iteraion.
+    store_32 [r1], r3
+    add r1, r1, 4
+    store_32 [r1], r3
+    add r1, r1, 4
+_fill32__entry:
+    ; Check if we can process more data in the vectorized loop.
+    cmp r1, r2
+    jbe _fill32__loop
+    ; The remaining amount of bytes `R` is `R = r2 + 8 - r1 = r2 - r1 mod 8`.
+    sub flags, r2, r1
+    ; Check if the third bit of the remainder is cleared.
+    jge _fill32__r4
+    ; Otherwise set 4 bytes.
+    store_32 [r1], r3
+    add r1, r1, 4
+_fill32__r4:
+    ; Check if the two least significant bits of the remainder are zero.
+    ja _fill32__ret
+    ; Handle the remaining bytes `R` individually, in reverse order.
+    add r2, r2, 4
+    ; `r1 + 4 - r2 = 4 - R`.
+    sub flags, r1, r2
+    ; Exclusive end point of the destination segment.
+    add r2, r2, 4
+    ; Shift out the least significant `8*(4 - R)` bits of the value.
+    lsl flags, flags, 3
+    lsr r3, r3, flags
+    jmp _fill32__loop2_entry
+_fill32__loop2:
+    sub r2, r2, 1
+    ; Write the least significant byte of the value...
+    store_8 [r2], r3
+    ; and then shift it out.
+    lsr r3, r3, 8
+_fill32__loop2_entry:
+    cmp r1, r2
+    jb _fill32__loop2
+_fill32__ret:
+    jmp r13

src/start.asm

@@ -0,0 +1,19 @@
+;@0 ; Reserve space for globals
+
+; First initialise the stack pointer
+nor sp, zr, 0xffff
+; Jump over the globals to user code
+jmp 0x100
+
+U32 0 ; 4 bytes
+
+; MAGIC_VALUE
+;@0x0c
+U32 0xb301534c
+
+; Pad with zeroes since the @addr feature is currently broken.
+; * https://discord.com/channels/828292123936948244/1545010596246847568
+;
+U1920 0  ; 240 bytes
+
+;@0x100 ; start of user code

src/stdlib.asm

@@ -0,0 +1,11 @@
+pub include bit
+pub include imath
+pub include array
+pub include console
+pub include mem
+pub include string
+pub include string_to_int
+pub include int_to_string
+
+; Needs to be last!
+pub include LUTs

src/string.asm

@@ -0,0 +1,33 @@
+; Compare two strings
+; Arguments:
+; r1 - Pointer to string 1
+; r2 - Pointer to string 2
+; Result:
+; r1:
+;   -  `0` if both segments are equal.
+;   - `<0` if the first segment is less than the second segment.
+;   - `>0` if the first segment is greater than the second segment.
+; flags - Compare result
+; Clobbers:
+; r3 - last byte of r1 tested
+; r4 - last byte of r2 tested
+pub compare:
+load_8 r3, [r1]
+add r1, r1, 1
+load_8 r4, [r2]
+add r2, r2, 1
+cmp zr, r3              ; End of string 1
+je done
+cmp zr, r4              ; End of string 2
+je done
+cmp r3, r4
+je compare              ; Loop, tail recursion, what's the difference
+done:
+cmp r3, r4
+; `flags` is the comparison result in the format of `cmp`. Convert it to the desired format.
+; 00 => 0x40000000 > 0
+; 01 => 0x00000000 = 0
+; 10 => 0xC0000000 < 0
+xor r1, flags, 1
+lsl r1, r1, 30
+jmp r13

src/string_to_int.asm

@@ -0,0 +1,188 @@
+; Internal register assignments:
+; r1 - Partially parsed output integer
+; r2 - Parsing position
+; r3 - Character being parsed
+; r4 - Set to -1 if the input is negative
+
+; Convert string to integer (akin to libc atoi(), strotoi())
+; Arguments:
+; r1 - Pointer to string
+; Result:
+; r1 - Parsed integer
+; r2 - Pointer to first rejected input byte
+; Clobbers:
+; flags
+; r3 - last character read
+; r4 - Negative marker
+; Note: Unless the input is "0", tail-calls into a base-specific specialization.
+pub auto:
+mov r2, r1
+mov r1, 0
+mov r4, 0
+load_8 r3, [r2]
+cmp r3, 0x2D ; '-'
+jne auto_positive
+sub r4, zr, 1           ; Set r4 to -1
+add r2, r2, 1
+auto_positive:
+load_16 r3, [r2]        ; 2-byte prefix "0b", "0o", "0x", etc.
+or r3, r3, 0x20         ; 2nd char to lower case
+add r2, r2, 2
+cmp r3, 0x3062 ; "0b"
+je bin_loop
+cmp r3, 0x306F ; "0o"
+je oct_loop
+cmp r3, 0x3078 ; "0x"
+je hex_loop
+sub r2, r2, 2           ; no matching prefix, move pointer back
+jmp dec_loop
+
+; Epilogue
+done:
+add r1, r1, r4          ; If r4 is -1, negate r1. Else it's 0 and no effect.
+xor r1, r1, r4
+mov flags, 0            ; No error
+jmp r13
+
+; Convert decimal string to integer
+; Arguments:
+; r1 - Pointer to string
+; Result:
+; r1 - Parsed integer
+; r2 - Pointer to first rejected input byte
+; Clobbers:
+; flags
+; r3 - last character read
+; r4 - Negative marker
+pub dec:
+mov r2, r1
+mov r1, 0
+mov r4, 0
+load_8 r3, [r2]
+cmp r3, 0x2D ; '-'
+jne dec_positive
+sub r4, zr, 1           ; Set r4 to -1
+add r2, r2, 1
+dec_loop:
+load_8 r3, [r2]
+dec_positive:
+sub r3, r3, 0x30 ; '0'
+cmp r3, 9
+ja done
+add r2, r2, 1
+lsl flags, r1, 2        ; Use flags to help multiply by 10
+add r1, r1, flags
+lsl r1, r1, 1
+add r1, r1, r3
+jmp dec_loop
+
+; Convert binary string to integer
+; Arguments:
+; r1 - Pointer to string
+; Result:
+; r1 - Parsed integer
+; r2 - Pointer to first rejected input byte
+; Clobbers:
+; flags
+; r3 - last character read
+; r4 - Negative marker
+pub bin:
+mov r2, r1
+mov r1, 0
+mov r4, 0
+load_8 r3, [r2]
+cmp r3, 0x2D ; '-'
+jne bin_positive
+sub r4, zr, 1           ; Set r4 to -1
+add r2, r2, 1
+bin_positive:
+load_16 r3, [r2]        ; check for prefix
+or r3, r3, 0x20         ; 2nd char to lower case
+cmp r3, 0x3062 ; "0b"
+jne bin_loop
+add r2, r2, 2
+bin_loop:
+load_8 r3, [r2]
+sub r3, r3, 0x30 ; '0'
+cmp r3, 1
+ja done
+add r2, r2, 1
+lsl r1, r1, 1
+add r1, r1, r3
+jmp bin_loop
+
+; Convert octal string to integer
+; Arguments:
+; r1 - Pointer to string
+; Result:
+; r1 - Parsed integer
+; r2 - Pointer to first rejected input byte
+; Clobbers:
+; flags
+; r3 - last character read
+; r4 - Negative marker
+pub oct:
+mov r2, r1
+mov r1, 0
+mov r4, 0
+load_8 r3, [r2]
+cmp r3, 0x2D ; '-'
+jne oct_positive
+sub r4, zr, 1           ; Set r4 to -1
+add r2, r2, 1
+oct_positive:
+load_16 r3, [r2]        ; check for prefix
+or r3, r3, 0x20         ; 2nd char to lower case
+cmp r3, 0x306F ; "0o"
+jne oct_loop
+add r2, r2, 2
+oct_loop:
+load_8 r3, [r2]
+sub r3, r3, 0x30 ; '0'
+cmp r3, 7
+ja done
+add r2, r2, 1
+lsl r1, r1, 3
+add r1, r1, r3
+jmp oct_loop
+
+; Convert hexadecimal string to integer
+; Arguments:
+; r1 - Pointer to string
+; Result:
+; r1 - Parsed integer
+; r2 - Pointer to first rejected input byte
+; Clobbers:
+; flags
+; r3 - last character read
+; r4 - Negative marker
+pub hex:
+mov r2, r1
+mov r1, 0
+mov r4, 0
+load_8 r3, [r2]
+cmp r3, 0x2D ; '-'
+jne hex_positive
+sub r4, zr, 1           ; Set r4 to -1
+add r2, r2, 1
+hex_positive:
+load_16 r3, [r2]        ; check for prefix
+or r3, r3, 0x20         ; 2nd char to lower case
+cmp r3, 0x3078 ; "0x"
+jne hex_loop
+add r2, r2, 2
+hex_loop:
+load_8 r3, [r2]
+sub r3, r3, 0x30 ; '0'
+cmp r3, 10
+jb hex_add
+sub r3, r3, 0x11 ; 'A' - '0'
+and r3, r3, 0xdf        ; to lower case
+cmp r3, 5               ; 0-5: 6 letters
+ja done
+add r3, r3, 10          ; Adjust for digits below
+hex_add:
+add r2, r2, 1
+lsl r1, r1, 4
+add r1, r1, r3
+jmp hex_loop

src/unsafe_mem.asm

@@ -0,0 +1,77 @@
+; int compare(uint8_t* a, uint8_t* b, size_t count);
+;   Compares two memory segment of equal length lexicographically.
+;   Temporarily modifies the byte at address `a + count`.
+;
+; Arguments:
+; - `r1`: A pointer to the first memory segment.
+; - `r2`: A pointer to the second memory segment.
+; - `r3`: The size of both memory segments.
+; Results:
+; - `r1`:
+;   -  `0` if both segments are equal.
+;   - `<0` if the first segment is less than the second segment.
+;   - `>0` if the first segment is greater than the second segment.
+pub compare:
+    cmp r1, r2
+    je _compare__is_eq
+    ; Exclusive end point of the second segment.
+    add r4, r3, r2
+    ; Exclusive end point of the first segment.
+    add r3, r3, r1
+    load_8 r6, [r3]
+    load_8 flags, [r4]
+    ; Check if the first bytes behind the sequences are equal.
+    cmp flags, r6
+    jne _compare__loop
+    ; Change the byte directly behind the first segment.
+    xor r4, r6, 1
+    ; This would be problematic if someone calls compare with a first segment
+    ; whose end point overlaps the program memory of this function.
+    store_8 [r3], r4
+_compare__loop:
+    load_32 r4, [r1]
+    add r1, r1, 4
+    load_32 r5, [r2]
+    add r2, r2, 4
+    ; Comparing two sequences of 4 bytes lexicographically is equivalent to
+    ; comparing the corresponding big endian 32 bit words.
+    cmp r4, r5
+    je _compare__loop
+    ; We overshot in the loop; decrement r1 again. (Only by 2, we backtrack the rest if necessary later)
+    sub r1, r1, 2
+    ; Restore the byte we changed.
+    store_8 [r3], r6
+    ; We encountered two different words. Figure out what byte they differ on.
+    xor r4, r4, r5
+    ; Store the flags for later, to figure out the return value.
+    mov r5, flags
+    ; Check if at least one of the two most significant bytes is not 0.
+    cmp r4, 0xffff
+    jbe _compare__low2
+    ; If it is, backtrack the remaining 2 indices.
+    ; Shift the most significant bytes to the least significant ones.
+    sub r1, r1, 2
+    lsr r4, r4, 16
+_compare__low2:
+    ; r1 now points to a non-zero 16 bit value.
+    ; If the 16 bit value at r1-2 is in-bounds, then it is 0.
+    ; Check if the most significant byte of the 16 bit value is 0.
+    cmp r4, 0xff
+    ja _compare__low1
+    ; If it is, our target is the least significant byte.
+    add r1, r1, 1
+_compare__low1:
+    ; Otherwise, the target is that non-zero byte.
+    ; Check if the target is out of bounds, i.e. the loop terminated through the "bounds check".
+    cmp r1, r3
+    jae _compare__is_eq
+    ; r5 is the comparison result in the format of `cmp`. Convert it to the desired format.
+    ; 00 => 0x40000000 > 0
+    ; 01 => 0x00000000 = 0
+    ; 10 => 0xC0000000 < 0
+    xor r1, r5, 1
+    lsl r1, r1, 30
+    jmp r13
+_compare__is_eq:
+    mov r1, 0
+    jmp r13

stdlib.asm

@@ -1,2 +0,0 @@
-pub include bit
-pub include imath

tests/README.md

@@ -0,0 +1,3 @@
+# Tests
+
+Tests for the standard library go here, tests are allowed to depend on the recommended spec.isa changes.

tests/int_to_string_test.asm

@@ -0,0 +1,62 @@
+; test harness for int_to_string
+; Registers:
+; r8 - test address
+; r9 - test method
+; r12 - end of tests address
+li r8, tests
+li r12, end_of_tests
+next_test:
+; Set up arguments and run test
+load_32 r1, [r8]        ; Input value
+li r2, scratch          ; Output buffer
+mov r3, 64              ; Output buffer size
+add r4, r8, 4           ; Base
+load_8 r4, [r4]
+mov r13, itoa_test_ret  ; return address
+jmp stdlib.int_to_string.auto
+itoa_test_ret:
+nop                     ; For breakpoint after itoa but before r1 clobber
+
+; Strcmp to check results
+add r1, r8, 5           ; expected output
+li r2, scratch          ; actual output
+mov r13, itoa_strcmp_ret
+jmp stdlib.string.compare
+itoa_strcmp_ret:
+
+; Verify results
+halt.ne
+
+; Next test
+add r8, r8, 0x40
+cmp r8, r12
+jl next_test
+
+; Done
+halt
+
+
+include ../src/stdlib
+
+@0x20000
+tests:
+; inlen is the number of input bytes the function is expected to consume
+; addr   int            base  result
+@0x20000 U32 0b0        U8 2  "0\0"
+@0x20040 U32 0xFFFFFFFF U8 2  "11111111111111111111111111111111\0"
+@0x20080 U32 0b101010   U8 2  "101010\0"
+@0x200c0 U32 0o0        U8 8  "0\0"
+@0x20100 U32 0o640      U8 8  "640\0"
+@0x20140 U32 0xFFFFFFFF U8 8  "37777777777\0"
+@0x20180 U32 0x0        U8 16 "0\0"
+@0x201c0 U32 0x32fF6    U8 16 "32FF6\0"
+@0x20200 U32 0xdeadbeef U8 16 "DEADBEEF\0"
+@0x20240 U32 0xFFFFFFFF U8 16 "FFFFFFFF\0"
+@0x20280 U32 0          U8 10 "0\0"
+@0x202c0 U32 42069      U8 10 "42069\0"
+@0x20300 U32 12345678   U8 10 "12345678\0"
+@0x20340 U32 99999999   U8 10 "99999999\0"
+@0x20380
+end_of_tests:
+scratch: U1024 0
+

tests/string_to_int_test.asm

@@ -0,0 +1,57 @@
+; test harness for string_to_int
+; Registers:
+; r8 - test address
+; r9 - expected result
+; r10 - actual length
+; r11 - expected length
+li r8, tests
+li r12, end_of_tests
+next_test:
+; Set up arguments and run test
+add r1, r8, 5          ; Start of test string
+mov r13, atoi_test_ret
+jmp stdlib.string_to_int.auto
+atoi_test_ret:
+
+; Load reference data
+load_32 r9, [r8]       ; Expected result
+sub r10, r2, r8
+sub r10, r10, 5        ; Actual string length
+add r11, r8, 4         ; Address of expected length
+load_8 r11, [r11]      ; Expected length
+
+; Verify results
+cmp r1, r9
+incorrect_result: jne incorrect_result
+cmp r10, r11
+incorrect_length: jne incorrect_length
+
+; Next test
+add r8, r8, 0x10
+cmp r8, r12
+jl next_test
+
+; Done
+success: jmp success
+
+include ../src/stdlib
+
+@0x20000
+tests:
+; inlen is the number of input bytes the function is expected to consume
+; addr  result          inlen  instr
+@0x20000 U32 0           U8 0   "\0"
+@0x20010 U32 0           U8 1   "0\0"
+@0x20020 U32 1           U8 1   "1\0"
+@0x20030 U32 2           U8 1   "2:\0"
+@0x20040 U32 42          U8 2   "42\0"
+@0x20050 U32 67          U8 2   "67lol\0"
+@0x20060 U32 0x69a       U8 5   "0x69a@\0"
+@0x20070 U32 0x4B4       U8 5   "0x4B4g\0"
+@0x20080 U32 0o23        U8 4   "0o239\0"
+@0x20090 U32 0b1011      U8 6   "0b1011\0"
+@0x200a0 U32 0b10001     U8 7   "0b100012\0"
+@0x200b0 U32 0xFFFFFFEB  U8 3   "-21\0"       ; Yuk
+@0x200c0
+end_of_tests:
+