mirror of https://github.com/acidanthera/audk.git
140 lines
4.8 KiB
ArmAsm
140 lines
4.8 KiB
ArmAsm
//
|
|
// 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
|
|
|
|
.text
|
|
.thumb
|
|
.syntax unified
|
|
.align 5
|
|
.type ASM_PFX(InternalMemCompareMem), %function
|
|
ASM_GLOBAL ASM_PFX(InternalMemCompareMem)
|
|
ASM_PFX(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, 0f
|
|
bne .Lloop_aligned
|
|
// End of performance-critical section -- one 32B cache line.
|
|
|
|
// Not reached the limit, must have found a diff.
|
|
0: 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, #3 // Bytes beyond alignment -> bits.
|
|
ldr data1, [src1], #4
|
|
rsb tmp1, tmp1, #32 // 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
|
|
1:
|
|
// Perhaps we can do better than this.
|
|
ldrb data1, [src1], #1
|
|
ldrb data2, [src2], #1
|
|
subs limit, limit, #1
|
|
it cs
|
|
cmpcs.n data1, data2
|
|
beq 1b
|
|
sub result, data1, data2
|
|
pop {r4-r8, pc}
|