SH-4 Registers (Windows CE 5.0)

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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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