SDCC calling convention
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By default, SDCC uses the stack to provide parameters to function calls, and uses the L. HL or DE - HL registers for return values depending on the size of the return value. SDCC starting in version 4.2.0 introduced changes to the calling conventions used.
| __sdcccall(0) | __sdcccall(1) | __z88dk_fastcall | |
|---|---|---|---|
| Return | |||
| 8 bits | L | A | L |
| 16 bits | HL | HL | HL |
| 32 bits | DE - HL | HL - DE | DE - HL |
| Parameters | |||
| 8 bits | Stack | A | L |
| 16 bits | Stack | HL | HL |
| 32 bits | Stack | HL - DE | HL - DE |
| 8 + 8 bits | Stack | A + L | Invalid |
| 8 + 16 bits | Stack | A + DE | Invalid |
| 16 + 16 bits | Stack | HL + DE | Invalid |
| 16 + 8 bits | Stack | HL + Stack | Invalid |