forked from TCShenanigans/symphony_stdlib
47 lines
1.8 KiB
Markdown
47 lines
1.8 KiB
Markdown
# Symphony Stdlib
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This is a standard library for symphony.
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It is both intended as a practical toolkit to develop more complex software as well as a teaching resource.
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If you just want to use the standard library [[stdlib.asm]] is your main header, include it after your code.
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If you are using it as a learning resource have a look at the [teaching folder](teaching).
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If you are intersted in contributing have a look at [[CONTRIBUTING.md]]
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---
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## ABI
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### Calling Convention
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| class | registers |
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| ----- | --------- |
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| n.a. | zr |
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| preserved | sp, r8 - r12 |
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| scratch | flags, r1 - r7 |
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| arguments | r1 - r7 |
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| result | r1-r7 |
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| return address | r13 |
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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.
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Arguments are passed in reverse order with the stack so:
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lowest address = 1st stack arg
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highest address = last stack arg
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Should a function return more values than fit into the 7 registers, the caller has to allocate space on the stack for them, and pass the pointer to that space in the next free argument register.
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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.
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This register points at the highest available address for results, with the 8th result being stored there, the 9th below it and so on.
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### Stack
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Grows downwards from 0xXXFE_0000 (so top of memory -0x1_0000).
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### Types
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#### String
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Strings are stored in memory as null terminated sequences of bytes encoding ascii characters.
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They should be passed by reference.
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#### Array
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Arrays are stored in memory with a reference to them being the tuple (pointer, length) stored in a register pair.
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Array elements may only have a size of 8/16/32 bits
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