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/*
* Copyright 2010 The Android Open Source Project
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
/* Changes:
* 2010-08-11 Steve McIntyre <steve.mcintyre@arm.com>
* Added small changes to the two functions to make them work on the
* specified number of 16- or 32-bit values rather than the original
* code which was specified as a count of bytes. More verbose comments
* to aid future maintenance.
*/
.text
.align 4
.syntax unified
.global arm_memset32
.type arm_memset32, %function
.global arm_memset16
.type arm_memset16, %function
/*
* Optimized memset functions for ARM.
*
* void arm_memset16(uint16_t* dst, uint16_t value, int count);
* void arm_memset32(uint32_t* dst, uint32_t value, int count);
*
*/
arm_memset16:
.fnstart
push {lr}
/* if count is equal to zero then abort */
teq r2, #0
ble .Lfinish
/* Multiply count by 2 - go from the number of 16-bit shorts
* to the number of bytes desired. */
mov r2, r2, lsl #1
/* expand the data to 32 bits */
orr r1, r1, r1, lsl #16
/* align to 32 bits */
tst r0, #2
strhne r1, [r0], #2
subne r2, r2, #2
/* Now jump into the main loop below. */
b .Lwork_32
.fnend
arm_memset32:
.fnstart
push {lr}
/* if count is equal to zero then abort */
teq r2, #0
ble .Lfinish
/* Multiply count by 4 - go from the number of 32-bit words to
* the number of bytes desired. */
mov r2, r2, lsl #2
.Lwork_32:
/* Set up registers ready for writing them out. */
mov ip, r1
mov lr, r1
/* Try to align the destination to a cache line. Assume 32
* byte (8 word) cache lines, it's the common case. */
rsb r3, r0, #0
ands r3, r3, #0x1C
beq .Laligned32
cmp r3, r2
andhi r3, r2, #0x1C
sub r2, r2, r3
/* (Optionally) write any unaligned leading bytes.
* (0-28 bytes, length in r3) */
movs r3, r3, lsl #28
stmiacs r0!, {r1, lr}
stmiacs r0!, {r1, lr}
stmiami r0!, {r1, lr}
movs r3, r3, lsl #2
strcs r1, [r0], #4
/* Now quickly loop through the cache-aligned data. */
.Laligned32:
mov r3, r1
1: subs r2, r2, #32
stmiahs r0!, {r1,r3,ip,lr}
stmiahs r0!, {r1,r3,ip,lr}
bhs 1b
add r2, r2, #32
/* (Optionally) store any remaining trailing bytes.
* (0-30 bytes, length in r2) */
movs r2, r2, lsl #28
stmiacs r0!, {r1,r3,ip,lr}
stmiami r0!, {r1,lr}
movs r2, r2, lsl #2
strcs r1, [r0], #4
strhmi lr, [r0], #2
.Lfinish:
pop {pc}
.fnend
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