Floating-Point Parameter Example
This example illustrates the rules for SH-4 argument passing.
Given the following declarations,
struct {
float x;
float y;
} point;
int myfunction(struct point p1,
float u,
struct point p2,
double v,
float w,
float x,
double y,
double z);
The following table shows the arrangement of non-floating-point arguments in the registers and on the stack for the function myfunction.
| Register | Description |
|---|---|
| R4: | p1.x, the first part of structure point 1 |
| R5: | p1.y, the second part of structure point 1 |
| R6: | Unused. This register would contain float u if using SH-3 calling convention or using varargs |
| R7: | p2.x, the first part of structure point 2 |
Stack offset 16-19 contains p2.y, second part of structure point p2.
The following table shows the arrangement of floating-point arguments in the registers and on the stack for the function myfunction.
| Register | Description |
|---|---|
| FR4: | Float u |
| FR5: | Float w // w fills in the gap left by putting double v into DR6 |
| DR6: | Double v |
| FR8: | Float x |
| FR9: | Unused |
| DR10: | Double y |
Stack offset 44-51 contains double z.
See Also
SH-4 Parameter Passing | Argument Area | Argument Block | Argument Block Mapping | SH-4 Functions with Variable Argument Lists
Last updated on Thursday, April 08, 2004
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