1 #------------------------------------------------------------------------------
3 # CopyMem() worker for ARM
5 # This file started out as C code that did 64 bit moves if the buffer was
6 # 32-bit aligned, else it does a byte copy. It also does a byte copy for
7 # any trailing bytes. It was updated to do 32-byte copies using stm/ldm.
9 # Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
10 # This program and the accompanying materials
11 # are licensed and made available under the terms and conditions of the BSD License
12 # which accompanies this distribution. The full text of the license may be found at
13 # http://opensource.org/licenses/bsd-license.php
15 # THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
16 # WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
18 #------------------------------------------------------------------------------
21 Copy Length bytes from Source to Destination. Overlap is OK.
25 @param Destination Target of copy
26 @param Source Place to copy from
27 @param Length Number of bytes to copy
35 OUT VOID *DestinationBuffer,
36 IN CONST VOID *SourceBuffer,
42 GCC_ASM_EXPORT(InternalMemCopyMem)
44 ASM_PFX(InternalMemCopyMem):
45 stmfd sp!, {r4-r11, lr}
46 // Save the input parameters in extra registers (r11 = destination, r14 = source, r12 = length)
52 memcopy_check_overlapped:
55 bcc memcopy_check_optim_default
56 // If (dest <= source). But with the previous condition -> If (dest == source)
59 // If (source + length < dest)
62 bcc memcopy_check_optim_default
68 b memcopy_check_optim_overlap
70 memcopy_check_optim_default:
71 // Check if we can use an optimized path ((length >= 32) && destination word-aligned && source word-aligned) for the memcopy (optimized path if r0 == 1)
83 memcopy_check_optim_overlap:
84 // r10 = dest_end, r14 = source_end
88 // Are we in the optimized case ((length >= 32) && dest_end word-aligned && source_end word-aligned)
98 memcopy_overlapped_non_optim:
99 // We read 1 byte from the end of the source buffer
105 // We write 1 byte at the end of the dest buffer
109 bne memcopy_overlapped_non_optim
112 // r10 = dest_end, r14 = source_end
114 // Are we in the optimized case ?
116 beq memcopy_overlapped_non_optim
118 // Optimized Overlapped - Read 32 bytes
124 // If length is less than 32 then disable optim
129 // Optimized Overlapped - Write 32 bytes
133 // while (length != 0)
134 bne memcopy_overlapped
137 memcopy_default_non_optim:
147 // r10 = dest, r14 = source
148 memcopy_default_loop:
150 beq memcopy_default_non_optim
152 // Optimized memcopy - Read 32 Bytes
157 // If length is less than 32 then disable optim
162 // Optimized memcopy - Write 32 Bytes
165 // while (length != 0)
166 bne memcopy_default_loop
170 ldmfd sp!, {r4-r11, pc}