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oot/asm/bzero.s
Tharo 7334ffa373
Improve the state of handwritten assembly files (#865)
* Format all handwritten asm and document some

* Use c preprocessor for constants

* Fix

* Fix PI_STATUS_ERROR, some label improvements

* Avoid hi/lo for constants

* Some more comments

* Properly mark functions as functions and their sizes

* Fix merge

* Improvements

* Review suggestions, rework procedure start/end macros to be more like libreultra

* Move IPL3 symbol definitions into ipl3.s

* Fix undefined_syms, add include and language guards to asm.h and fix the comment in gbi.h

* Consistent hex capitalization, add some MIPS builtin defines to CC_CHECK to behave properly

* Add -no-pad-sections assembler option and clean up alignment in gu files and bzero

* Further suggestions and improvements

* Matrix conversion function clarifications

* Fix passing AVOID_UB to gcc

* Suggestions

* Suggestions, global interrupt mask improvements

* Further suggestions, interrupt mask comments

* Comments fixes, rdb.h

* Switch from # comments to // comments, remove unnecesary .set gp=64 directives

* Further review suggestions

* Missed one
2022-05-01 01:03:22 +02:00

65 lines
1.4 KiB
ArmAsm

#include "ultra64/asm.h"
.set noat
.set noreorder
.section .text
.balign 16
LEAF(bzero)
slti $at, $a1, 0xC
bnez $at, bytezero
negu $v1, $a0
andi $v1, $v1, 3
beqz $v1, blkzero
subu $a1, $a1, $v1
swl $zero, ($a0)
addu $a0, $a0, $v1
blkzero:
// align backwards to 0x20
li $at, ~0x1F
and $a3, $a1, $at
// If the result is zero, the amount to zero is less than 0x20 bytes
beqz $a3, wordzero
subu $a1, $a1, $a3
// zero in blocks of 0x20 at a time
addu $a3, $a3, $a0
1:
addiu $a0, $a0, 0x20
sw $zero, -0x20($a0)
sw $zero, -0x1C($a0)
sw $zero, -0x18($a0)
sw $zero, -0x14($a0)
sw $zero, -0x10($a0)
sw $zero, -0xC($a0)
sw $zero, -8($a0)
bne $a0, $a3, 1b
sw $zero, -4($a0)
wordzero:
// align backwards to 0x4
li $at, ~3
and $a3, $a1, $at
// If the result is zero, the amount to zero is less than 0x4 bytes
beqz $a3, bytezero
subu $a1, $a1, $a3
// zero one word at a time
addu $a3, $a3, $a0
1:
addiu $a0, $a0, 4
bne $a0, $a3, 1b
sw $zero, -4($a0)
bytezero:
// test if nothing left to zero
blez $a1, zerodone
nop
// zero one byte at a time
addu $a1, $a1, $a0
1:
addiu $a0, $a0, 1
bne $a0, $a1, 1b
sb $zero, -1($a0)
zerodone:
jr $ra
nop
END(bzero)