SH-4 Registers (Windows CE 5.0)
The SH-4 has 16 general-purpose registers. The following table shows the roles assigned to these registers.
| Register | Description |
|---|---|
| R0 | Serves as a temporary register when expanding assembly language pseudo-instructions, and holds function return values.
In addition, R0 serves as an implicit source or destination in byte and 16-bit operations. Not preserved. |
| R1-R3 | Serve as temporary registers Not preserved |
| R4-R7 | Hold the first four words of integer and non-scalar incoming arguments. The argument build area provides space into which R4 through R7 holding arguments may spill.
Not preserved. |
| R8-R13 | Serve as permanent registers Preserved |
| R14 | Serves as the default frame pointer. Any other permanent register may serve as the frame pointer, and leaf routines may use a temporary register as the frame pointer.
Preserved. |
| R15 | Serves as the stack pointer or as a permanent register Preserved. |
The SH-4 has two banks of 16 floating-point registers designated Bank0 and Bank1. This specification does not define the use of Bank1. This calling convention assigns the following roles to the SH-4 Bank0 floating-point registers.
| Double-Precision Register |
Single-Precision Register |
Description |
|---|---|---|
| DR0 | FR0 FR1 |
Hold function return values. DR0 is another name for FR0 and FR1 as a pair. |
| DR2 | FR2-FR3 | Serve as temporary registers. DR2 is another name for FR2 and FR3 as a pair. Not preserved |
| DR4-DR10 | FR4-FR11 | Hold single- or double-precision floating-point arguments. The argument build area also provides space into which floating-point registers holding arguments may spill. |
| DR12-DR14 | FR12-FR15 | Serve as permanent registers Preserved |
The floating-point status control affects the behavior of some floating-point instructions. The section SH-4 Prolog and Epilog defines the use of the PR, SZ, and FR bits within prologs and epilogs.
See Also
SH-4 Stack Frame Layout | SH-4 Prolog and Epilog
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