mirror of
https://github.com/CloverHackyColor/CloverBootloader.git
synced 2024-11-24 11:45:27 +01:00
141 lines
4.7 KiB
NASM
141 lines
4.7 KiB
NASM
;
|
|
; Copyright (c) 2013 - 2016, Linaro Limited
|
|
; All rights reserved.
|
|
;
|
|
; Redistribution and use in source and binary forms, with or without
|
|
; modification, are permitted provided that the following conditions are met:
|
|
; * Redistributions of source code must retain the above copyright
|
|
; notice, this list of conditions and the following disclaimer.
|
|
; * Redistributions in binary form must reproduce the above copyright
|
|
; notice, this list of conditions and the following disclaimer in the
|
|
; documentation and/or other materials provided with the distribution.
|
|
; * Neither the name of the Linaro nor the
|
|
; names of its contributors may be used to endorse or promote products
|
|
; derived from this software without specific prior written permission.
|
|
;
|
|
; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
|
; A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
|
; HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
|
; SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
|
; LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
; DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
; THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
; OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
;
|
|
|
|
; Parameters and result.
|
|
#define src1 r0
|
|
#define src2 r1
|
|
#define limit r2
|
|
#define result r0
|
|
|
|
; Internal variables.
|
|
#define data1 r3
|
|
#define data2 r4
|
|
#define limit_wd r5
|
|
#define diff r6
|
|
#define tmp1 r7
|
|
#define tmp2 r12
|
|
#define pos r8
|
|
#define mask r14
|
|
|
|
EXPORT InternalMemCompareMem
|
|
THUMB
|
|
AREA CompareMem, CODE, READONLY
|
|
|
|
InternalMemCompareMem
|
|
push {r4-r8, lr}
|
|
eor tmp1, src1, src2
|
|
tst tmp1, #3
|
|
bne Lmisaligned4
|
|
ands tmp1, src1, #3
|
|
bne Lmutual_align
|
|
add limit_wd, limit, #3
|
|
nop.w
|
|
lsr limit_wd, limit_wd, #2
|
|
|
|
; Start of performance-critical section -- one 32B cache line.
|
|
Lloop_aligned
|
|
ldr data1, [src1], #4
|
|
ldr data2, [src2], #4
|
|
Lstart_realigned
|
|
subs limit_wd, limit_wd, #1
|
|
eor diff, data1, data2 ; Non-zero if differences found.
|
|
cbnz diff, L0
|
|
bne Lloop_aligned
|
|
; End of performance-critical section -- one 32B cache line.
|
|
|
|
; Not reached the limit, must have found a diff.
|
|
L0
|
|
cbnz limit_wd, Lnot_limit
|
|
|
|
// Limit % 4 == 0 => all bytes significant.
|
|
ands limit, limit, #3
|
|
beq Lnot_limit
|
|
|
|
lsl limit, limit, #3 // Bits -> bytes.
|
|
mov mask, #~0
|
|
lsl mask, mask, limit
|
|
bic data1, data1, mask
|
|
bic data2, data2, mask
|
|
|
|
orr diff, diff, mask
|
|
|
|
Lnot_limit
|
|
rev diff, diff
|
|
rev data1, data1
|
|
rev data2, data2
|
|
|
|
; The MS-non-zero bit of DIFF marks either the first bit
|
|
; that is different, or the end of the significant data.
|
|
; Shifting left now will bring the critical information into the
|
|
; top bits.
|
|
clz pos, diff
|
|
lsl data1, data1, pos
|
|
lsl data2, data2, pos
|
|
|
|
; But we need to zero-extend (char is unsigned) the value and then
|
|
; perform a signed 32-bit subtraction.
|
|
lsr data1, data1, #28
|
|
sub result, data1, data2, lsr #28
|
|
pop {r4-r8, pc}
|
|
|
|
Lmutual_align
|
|
; Sources are mutually aligned, but are not currently at an
|
|
; alignment boundary. Round down the addresses and then mask off
|
|
; the bytes that precede the start point.
|
|
bic src1, src1, #3
|
|
bic src2, src2, #3
|
|
add limit, limit, tmp1 ; Adjust the limit for the extra.
|
|
lsl tmp1, tmp1, #2 ; Bytes beyond alignment -> bits.
|
|
ldr data1, [src1], #4
|
|
neg tmp1, tmp1 ; Bits to alignment -32.
|
|
ldr data2, [src2], #4
|
|
mov tmp2, #~0
|
|
|
|
; Little-endian. Early bytes are at LSB.
|
|
lsr tmp2, tmp2, tmp1 ; Shift (tmp1 & 31).
|
|
add limit_wd, limit, #3
|
|
orr data1, data1, tmp2
|
|
orr data2, data2, tmp2
|
|
lsr limit_wd, limit_wd, #2
|
|
b Lstart_realigned
|
|
|
|
Lmisaligned4
|
|
sub limit, limit, #1
|
|
L1
|
|
// Perhaps we can do better than this.
|
|
ldrb data1, [src1], #1
|
|
ldrb data2, [src2], #1
|
|
subs limit, limit, #1
|
|
it cs
|
|
cmpcs data1, data2
|
|
beq L1
|
|
sub result, data1, data2
|
|
pop {r4-r8, pc}
|
|
|
|
END
|