Merge branch 'abi-docs'

docs/abi.md

@@ -0,0 +1,18 @@
+# Application Binary Interface
+The ZDK project specifies an Application Binary Interface (ABI) employed across its compilers, tools, and libraries. This ABI is based on the [cdecl](https://en.wikipedia.org/wiki/X86_calling_conventions#cdecl) calling convention and adheres to conventional C symbol naming rules.
+
+## Function Naming
+In contrast to traditional 8-bit compilers, ZDK functions do not have an underscore prefix. This approach simplifies the compilation and linking processes, resulting in cleaner and more intuitive function names.
+
+## Function Parameters
+- Parameters are pushed onto the stack from right to left.
+- The caller is responsible for cleaning up the stack after the function returns.
+
+## Return Values
+- Single-byte values are returned in the `A` register.
+- Multi-byte values are returned with the most significant word in the `DE` register pair and the least significant word in the `HL` register pair.
+
+## Register Usage
+- Functions can freely use the `A`, `B`, `C`, `D`, `E`, `H`, `L` registers and their pairs without restrictions.
+- The caller must save and restore any registers it needs to preserve across function calls.
+- If the `IX` register is used (e.g., for indexing arguments or local variables), the callee must preserve it.

mkdocs.yml

@@ -7,9 +7,9 @@ edit_uri: edit/main/docs/
 
 nav:
   - 'index.md'
+  - 'abi.md'
   - Development:
     - 'development/compiler-debugging.md'
-  - 'calling-convention.md'
 
 theme:
   name: material