64 lines
1.9 KiB
ArmAsm
64 lines
1.9 KiB
ArmAsm
// ----------------------------------------------------------------------------
|
|
// Copyright (c) 1992 Olivetti
|
|
//
|
|
// File: subrout.s
|
|
//
|
|
// Description: Assembly subroutines used throughout the ROM.
|
|
// ----------------------------------------------------------------------------
|
|
|
|
//
|
|
// include header files
|
|
//
|
|
|
|
#include <ksmips.h>
|
|
|
|
.text
|
|
.set noreorder
|
|
|
|
|
|
// ----------------------------------------------------------------------------
|
|
// PROCEDURE: StatusReg:
|
|
//
|
|
// DESCRIPTION: This function updates the CPU status register
|
|
// ( CPU0 reg. 12 ).
|
|
// The register is "&" with a0 and "|" with a1.
|
|
// The old register value is returned to the calling
|
|
// routine in v0.
|
|
//
|
|
//
|
|
// ARGUMENTS: a0 & with Status register
|
|
// a1 | with Status register
|
|
//
|
|
// RETURN: v0 Old Status register value
|
|
//
|
|
// ASSUMPTIONS: none
|
|
//
|
|
// CALLS: none
|
|
//
|
|
// GLOBALS: none
|
|
//
|
|
// NOTES: none
|
|
// ----------------------------------------------------------------------------
|
|
//
|
|
LEAF_ENTRY(StatusReg)
|
|
|
|
.set noat
|
|
|
|
//
|
|
// The first argument is "&" and the second is "|" with the status register.
|
|
//
|
|
|
|
mfc0 v0, psr // read status register
|
|
nop // required by mfc before using v0
|
|
nop // to avoid hazards
|
|
move t0, v0 // make a copy of it
|
|
and t0, t0, a0 // "&" with 1st parameter
|
|
or t0, t0, a1 // "|" with 2nd parameter
|
|
mtc0 t0, psr // write status register
|
|
nop
|
|
nop
|
|
j ra // return
|
|
nop // required by "j ra"
|
|
|
|
.end StatusReg
|