;------------------------------------------------------------------------------ | |
; | |
; CopyMem() worker for ARM | |
; | |
; This file started out as C code that did 64 bit moves if the buffer was | |
; 32-bit aligned, else it does a byte copy. It also does a byte copy for | |
; any trailing bytes. It was updated to do 32-byte copies using stm/ldm. | |
; | |
; Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR> | |
; This program and the accompanying materials | |
; are licensed and made available under the terms and conditions of the BSD License | |
; which accompanies this distribution. The full text of the license may be found at | |
; http://opensource.org/licenses/bsd-license.php | |
; | |
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, | |
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. | |
; | |
;------------------------------------------------------------------------------ | |
/** | |
Copy Length bytes from Source to Destination. Overlap is OK. | |
This implementation | |
@param Destination Target of copy | |
@param Source Place to copy from | |
@param Length Number of bytes to copy | |
@return Destination | |
VOID * | |
EFIAPI | |
InternalMemCopyMem ( | |
OUT VOID *DestinationBuffer, | |
IN CONST VOID *SourceBuffer, | |
IN UINTN Length | |
) | |
**/ | |
EXPORT InternalMemCopyMem | |
AREA AsmMemStuff, CODE, READONLY | |
InternalMemCopyMem | |
stmfd sp!, {r4-r11, lr} | |
// Save the input parameters in extra registers (r11 = destination, r14 = source, r12 = length) | |
mov r11, r0 | |
mov r10, r0 | |
mov r12, r2 | |
mov r14, r1 | |
memcopy_check_overlapped | |
cmp r11, r1 | |
// If (dest < source) | |
bcc memcopy_check_optim_default | |
// If (dest <= source). But with the previous condition -> If (dest == source) | |
bls memcopy_end | |
// If (source + length < dest) | |
rsb r3, r1, r11 | |
cmp r12, r3 | |
bcc memcopy_check_optim_default | |
// If (length == 0) | |
cmp r12, #0 | |
beq memcopy_end | |
b memcopy_check_optim_overlap | |
memcopy_check_optim_default | |
// Check if we can use an optimized path ((length >= 32) && destination word-aligned && source word-aligned) for the memcopy (optimized path if r0 == 1) | |
tst r0, #0xF | |
movne r0, #0 | |
bne memcopy_default | |
tst r1, #0xF | |
movne r3, #0 | |
moveq r3, #1 | |
cmp r2, #31 | |
movls r0, #0 | |
andhi r0, r3, #1 | |
b memcopy_default | |
memcopy_check_optim_overlap | |
// r10 = dest_end, r14 = source_end | |
add r10, r11, r12 | |
add r14, r12, r1 | |
// Are we in the optimized case ((length >= 32) && dest_end word-aligned && source_end word-aligned) | |
cmp r2, #31 | |
movls r0, #0 | |
movhi r0, #1 | |
tst r10, #0xF | |
movne r0, #0 | |
tst r14, #0xF | |
movne r0, #0 | |
b memcopy_overlapped | |
memcopy_overlapped_non_optim | |
// We read 1 byte from the end of the source buffer | |
sub r3, r14, #1 | |
sub r12, r12, #1 | |
ldrb r3, [r3, #0] | |
sub r2, r10, #1 | |
cmp r12, #0 | |
// We write 1 byte at the end of the dest buffer | |
sub r10, r10, #1 | |
sub r14, r14, #1 | |
strb r3, [r2, #0] | |
bne memcopy_overlapped_non_optim | |
b memcopy_end | |
// r10 = dest_end, r14 = source_end | |
memcopy_overlapped | |
// Are we in the optimized case ? | |
cmp r0, #0 | |
beq memcopy_overlapped_non_optim | |
// Optimized Overlapped - Read 32 bytes | |
sub r14, r14, #32 | |
sub r12, r12, #32 | |
cmp r12, #31 | |
ldmia r14, {r2-r9} | |
// If length is less than 32 then disable optim | |
movls r0, #0 | |
cmp r12, #0 | |
// Optimized Overlapped - Write 32 bytes | |
sub r10, r10, #32 | |
stmia r10, {r2-r9} | |
// while (length != 0) | |
bne memcopy_overlapped | |
b memcopy_end | |
memcopy_default_non_optim | |
// Byte copy | |
ldrb r3, [r14], #1 | |
sub r12, r12, #1 | |
strb r3, [r10], #1 | |
memcopy_default | |
cmp r12, #0 | |
beq memcopy_end | |
// r10 = dest, r14 = source | |
memcopy_default_loop | |
cmp r0, #0 | |
beq memcopy_default_non_optim | |
// Optimized memcopy - Read 32 Bytes | |
sub r12, r12, #32 | |
cmp r12, #31 | |
ldmia r14!, {r2-r9} | |
// If length is less than 32 then disable optim | |
movls r0, #0 | |
cmp r12, #0 | |
// Optimized memcopy - Write 32 Bytes | |
stmia r10!, {r2-r9} | |
// while (length != 0) | |
bne memcopy_default_loop | |
memcopy_end | |
mov r0, r11 | |
ldmfd sp!, {r4-r11, pc} | |
END | |