/*
* linux/arch/arm/lib/csumpartialcopygeneric.S
*
* Copyright (C) 1995-2001 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
/*
* unsigned int
* csum_partial_copy_xxx(const char *src, char *dst, int len, int sum, )
* r0 = src, r1 = dst, r2 = len, r3 = sum
* Returns : r0 = checksum
*
* Note that 'tst' and 'teq' preserve the carry flag.
*/
src .req r0
dst .req r1
len .req r2
sum .req r3
.zero: mov r0, sum
load_regs ea
/*
* Align an unaligned destination pointer. We know that
* we have >= 8 bytes here, so we don't need to check
* the length. Note that the source pointer hasn't been
* aligned yet.
*/
.dst_unaligned: tst dst, #1
beq .dst_16bit
load1b ip
sub len, len, #1
adcs sum, sum, ip, put_byte_1 @ update checksum
strb ip, [dst], #1
tst dst, #2
moveq pc, lr @ dst is now 32bit aligned
.dst_16bit: load2b r8, ip
sub len, len, #2
adcs sum, sum, r8, put_byte_0
strb r8, [dst], #1
adcs sum, sum, ip, put_byte_1
strb ip, [dst], #1
mov pc, lr @ dst is now 32bit aligned
/*
* Handle 0 to 7 bytes, with any alignment of source and
* destination pointers. Note that when we get here, C = 0
*/
.less8: teq len, #0 @ check for zero count
beq .zero
/* we must have at least one byte. */
tst dst, #1 @ dst 16-bit aligned
beq .less8_aligned
/* Align dst */
load1b ip
sub len, len, #1
adcs sum, sum, ip, put_byte_1 @ update checksum
strb ip, [dst], #1
tst len, #6
beq .less8_byteonly
1: load2b r8, ip
sub len, len, #2
adcs sum, sum, r8, put_byte_0
strb r8, [dst], #1
adcs sum, sum, ip, put_byte_1
strb ip, [dst], #1
.less8_aligned: tst len, #6
bne 1b
.less8_byteonly:
tst len, #1
beq .done
load1b r8
adcs sum, sum, r8, put_byte_0 @ update checksum
strb r8, [dst], #1
b .done
FN_ENTRY
mov ip, sp
save_regs
sub fp, ip, #4
cmp len, #8 @ Ensure that we have at least
blo .less8 @ 8 bytes to copy.
adds sum, sum, #0 @ C = 0
tst dst, #3 @ Test destination alignment
blne .dst_unaligned @ align destination, return here
/*
* Ok, the dst pointer is now 32bit aligned, and we know
* that we must have more than 4 bytes to copy. Note
* that C contains the carry from the dst alignment above.
*/
tst src, #3 @ Test source alignment
bne .src_not_aligned
/* Routine for src & dst aligned */
bics ip, len, #15
beq 2f
1: load4l r4, r5, r6, r7
stmia dst!, {r4, r5, r6, r7}
adcs sum, sum, r4
adcs sum, sum, r5
adcs sum, sum, r6
adcs sum, sum, r7
sub ip, ip, #16
teq ip, #0
bne 1b
2: ands ip, len, #12
beq 4f
tst ip, #8
beq 3f
load2l r4, r5
stmia dst!, {r4, r5}
adcs sum, sum, r4
adcs sum, sum, r5
tst ip, #4
beq 4f
3: load1l r4
str r4, [dst], #4
adcs sum, sum, r4
4: ands len, len, #3
beq .done
load1l r4
tst len, #2
mov r5, r4, get_byte_0
beq .exit
adcs sum, sum, r4, push #16
strb r5, [dst], #1
mov r5, r4, get_byte_1
strb r5, [dst], #1
mov r5, r4, get_byte_2
.exit: tst len, #1
strneb r5, [dst], #1
andne r5, r5, #255
adcnes sum, sum, r5, put_byte_0
/*
* If the dst pointer was not 16-bit aligned, we
* need to rotate the checksum here to get around
* the inefficient byte manipulations in the
* architecture independent code.
*/
.done: adc r0, sum, #0
ldr sum, [sp, #0] @ dst
tst sum, #1
movne r0, r0, ror #8
load_regs ea
.src_not_aligned:
adc sum, sum, #0 @ include C from dst alignment
and ip, src, #3
bic src, src, #3
load1l r5
cmp ip, #2
beq .src2_aligned
bhi .src3_aligned
mov r4, r5, pull #8 @ C = 0
bics ip, len, #15
beq 2f
1: load4l r5, r6, r7, r8
orr r4, r4, r5, push #24
mov r5, r5, pull #8
orr r5, r5, r6, push #24
mov r6, r6, pull #8
orr r6, r6, r7, push #24
mov r7, r7, pull #8
orr r7, r7, r8, push #24
stmia dst!, {r4, r5, r6, r7}
adcs sum, sum, r4
adcs sum, sum, r5
adcs sum, sum, r6
adcs sum, sum, r7
mov r4, r8, pull #8
sub ip, ip, #16
teq ip, #0
bne 1b
2: ands ip, len, #12
beq 4f
tst ip, #8
beq 3f
load2l r5, r6
orr r4, r4, r5, push #24
mov r5, r5, pull #8
orr r5, r5, r6, push #24
stmia dst!, {r4, r5}
adcs sum, sum, r4
adcs sum, sum, r5
mov r4, r6, pull #8
tst ip, #4
beq 4f
3: load1l r5
orr r4, r4, r5, push #24
str r4, [dst], #4
adcs sum, sum, r4
mov r4, r5, pull #8
4: ands len, len, #3
beq .done
mov r5, r4, get_byte_0
tst len, #2
beq .exit
adcs sum, sum, r4, push #16
strb r5, [dst], #1
mov r5, r4, get_byte_1
strb r5, [dst], #1
mov r5, r4, get_byte_2
b .exit
.src2_aligned: mov r4, r5, pull #16
adds sum, sum, #0
bics ip, len, #15
beq 2f
1: load4l r5, r6, r7, r8
orr r4, r4, r5, push #16
mov r5, r5, pull #16
orr r5, r5, r6, push #16
mov r6, r6, pull #16
orr r6, r6, r7, push #16
mov r7, r7, pull #16
orr r7, r7, r8, push #16
stmia dst!, {r4, r5, r6, r7}
adcs sum, sum, r4
adcs sum, sum, r5
adcs sum, sum, r6
adcs sum, sum, r7
mov r4, r8, pull #16
sub ip, ip, #16
teq ip, #0
bne 1b
2: ands ip, len, #12
beq 4f
tst ip, #8
beq 3f
load2l r5, r6
orr r4, r4, r5, push #16
mov r5, r5, pull #16
orr r5, r5, r6, push #16
stmia dst!, {r4, r5}
adcs sum, sum, r4
adcs sum, sum, r5
mov r4, r6, pull #16
tst ip, #4
beq 4f
3: load1l r5
orr r4, r4, r5, push #16
str r4, [dst], #4
adcs sum, sum, r4
mov r4, r5, pull #16
4: ands len, len, #3
beq .done
mov r5, r4, get_byte_0
tst len, #2
beq .exit
adcs sum, sum, r4
strb r5, [dst], #1
mov r5, r4, get_byte_1
strb r5, [dst], #1
tst len, #1
beq .done
load1b r5
b .exit
.src3_aligned: mov r4, r5, pull #24
adds sum, sum, #0
bics ip, len, #15
beq 2f
1: load4l r5, r6, r7, r8
orr r4, r4, r5, push #8
mov r5, r5, pull #24
orr r5, r5, r6, push #8
mov r6, r6, pull #24
orr r6, r6, r7, push #8
mov r7, r7, pull #24
orr r7, r7, r8, push #8
stmia dst!, {r4, r5, r6, r7}
adcs sum, sum, r4
adcs sum, sum, r5
adcs sum, sum, r6
adcs sum, sum, r7
mov r4, r8, pull #24
sub ip, ip, #16
teq ip, #0
bne 1b
2: ands ip, len, #12
beq 4f
tst ip, #8
beq 3f
load2l r5, r6
orr r4, r4, r5, push #8
mov r5, r5, pull #24
orr r5, r5, r6, push #8
stmia dst!, {r4, r5}
adcs sum, sum, r4
adcs sum, sum, r5
mov r4, r6, pull #24
tst ip, #4
beq 4f
3: load1l r5
orr r4, r4, r5, push #8
str r4, [dst], #4
adcs sum, sum, r4
mov r4, r5, pull #24
4: ands len, len, #3
beq .done
mov r5, r4, get_byte_0
tst len, #2
beq .exit
strb r5, [dst], #1
adcs sum, sum, r4
load1l r4
mov r5, r4, get_byte_0
strb r5, [dst], #1
adcs sum, sum, r4, push #24
mov r5, r4, get_byte_1
b .exit
