clarify stack arguments

CONTRIBUTING.md

@@ -0,0 +1,25 @@
+# Contributing
+
+## Code of Conduct
+Be nice, we are all just doing this to have fun
+
+## General rules
+- All text (names, comments, etc.) has to be in English
+- You are responsible for ensuring that you have the rights for us to use the code you contribute to the project
+- follow the guidelines, for code, documentation, etc.
+- all code has to work with the standard symphony ISA
+
+## Documenting Functions
+All functions in the standard library should follow the following outline:
+```
+; <description>
+; Arguments: <which register contains what argument>
+; Result: <what is the result, and where is it stored>
+; Clobbers: <list of registers that are clobbered>
+fn_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

README.md

@@ -20,19 +20,28 @@ If you are intersted in contributing have a look at [[CONTRIBUTING.md]]
 | n.a. | zr |
 | preserved | sp, r8 - r12 |
 | scratch | flags, r1 - r7 |
-| arguments | r1 - r5, r6 = stack args, r7 = stack res |
-| result | r1 = low word, r2 = high word |
+| arguments | r1 - r7 |
+| result | r1-r7 |
 | return address | r13 |
 
-### Stack
-grows downwards from top of memory
-arguments are passed in reverse order with the stack so:
+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.
+Arguments are passed in reverse order with the stack so:
 lowest address = 1st stack arg
 highest address = last stack arg
 
+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 r7.
+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 r7.
+r7 points at the highest available address for results, with the 8th result being stored there, the 9th below it and so on.
+
+### Stack
+Grows downwards from top of memory.
+
 ### Types
 
 #### String
 Strings are stored in memory as null terminated sequences of bytes encoding ascii characters.
 They should be passed by reference.
 
+#### Array
+Arrays are stored in memory with a reference to them being the tuple (pointer, length) stored in a register pair.
+Array elements may only have a size of 8/16/32 bits