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Return Values
C functions (which are declared as follows) may return a single value with a specified type.
<[>type<]> funcname (<[>args<]>)
where:
| type | is the type of the value returned from the function. If no type is specified, int is assumed. |
| funcname | is the name of the function. |
| args | is the argument list for the function. |
Return values are always returned in registers depending on the return value type. The following table lists return types and the registers used for each.
| Return Type | Register(s) | Description |
|---|---|---|
| bit | R4.0 | |
| signed char unsigned char |
RL4 | |
| signed int unsigned int |
R4 | |
| signed long unsigned long |
R4-R5 | LSB in R4, MSB in R5. |
| float | R4-R5 | 32-bit IEEE format, exponent and sign in R5. |
| double | R4-R7 | 64-bit IEEE format, exponent and sign in R7. |
| near (2-byte) pointer | R4 | |
| far (4-byte) pointer huge (4-byte) pointer |
R4-R5 | Offset in R4, selector in R5. |
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