1 ;------------------------------------------------------------------------------ 2 ; 3 ; CopyMem() worker for ARM 4 ; 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. 8 ; 9 ; Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR> 10 ; Copyright (c) 2016, Linaro Ltd. All rights reserved.<BR> 11 ; This program and the accompanying materials 12 ; are licensed and made available under the terms and conditions of the BSD License 13 ; which accompanies this distribution. The full text of the license may be found at 14 ; http://opensource.org/licenses/bsd-license.php 15 ; 16 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 17 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. 18 ; 19 ;------------------------------------------------------------------------------ 20 21 EXPORT InternalMemCopyMem 22 AREA SetMem, CODE, READONLY 23 THUMB 24 25 InternalMemCopyMem 26 stmfd sp!, {r4-r11, lr} 27 // Save the input parameters in extra registers (r11 = destination, r14 = source, r12 = length) 28 mov r11, r0 29 mov r10, r0 30 mov r12, r2 31 mov r14, r1 32 33 memcopy_check_overlapped 34 cmp r11, r1 35 // If (dest < source) 36 bcc memcopy_check_optim_default 37 38 // If (source + length < dest) 39 rsb r3, r1, r11 40 cmp r12, r3 41 bcc memcopy_check_optim_default 42 b memcopy_check_optim_overlap 43 44 memcopy_check_optim_default 45 // Check if we can use an optimized path ((length >= 32) && destination word-aligned && source word-aligned) for the memcopy (optimized path if r0 == 1) 46 tst r0, #0xF 47 movne r0, #0 48 bne memcopy_default 49 tst r1, #0xF 50 movne r3, #0 51 moveq r3, #1 52 cmp r2, #31 53 movls r0, #0 54 andhi r0, r3, #1 55 b memcopy_default 56 57 memcopy_check_optim_overlap 58 // r10 = dest_end, r14 = source_end 59 add r10, r11, r12 60 add r14, r12, r1 61 62 // Are we in the optimized case ((length >= 32) && dest_end word-aligned && source_end word-aligned) 63 cmp r2, #31 64 movls r0, #0 65 movhi r0, #1 66 tst r10, #0xF 67 movne r0, #0 68 tst r14, #0xF 69 movne r0, #0 70 b memcopy_overlapped 71 72 memcopy_overlapped_non_optim 73 // We read 1 byte from the end of the source buffer 74 sub r3, r14, #1 75 sub r12, r12, #1 76 ldrb r3, [r3, #0] 77 sub r2, r10, #1 78 cmp r12, #0 79 // We write 1 byte at the end of the dest buffer 80 sub r10, r10, #1 81 sub r14, r14, #1 82 strb r3, [r2, #0] 83 bne memcopy_overlapped_non_optim 84 b memcopy_end 85 86 // r10 = dest_end, r14 = source_end 87 memcopy_overlapped 88 // Are we in the optimized case ? 89 cmp r0, #0 90 beq memcopy_overlapped_non_optim 91 92 // Optimized Overlapped - Read 32 bytes 93 sub r14, r14, #32 94 sub r12, r12, #32 95 cmp r12, #31 96 ldmia r14, {r2-r9} 97 98 // If length is less than 32 then disable optim 99 movls r0, #0 100 101 cmp r12, #0 102 103 // Optimized Overlapped - Write 32 bytes 104 sub r10, r10, #32 105 stmia r10, {r2-r9} 106 107 // while (length != 0) 108 bne memcopy_overlapped 109 b memcopy_end 110 111 memcopy_default_non_optim 112 // Byte copy 113 ldrb r3, [r14], #1 114 sub r12, r12, #1 115 strb r3, [r10], #1 116 117 memcopy_default 118 cmp r12, #0 119 beq memcopy_end 120 121 // r10 = dest, r14 = source 122 memcopy_default_loop 123 cmp r0, #0 124 beq memcopy_default_non_optim 125 126 // Optimized memcopy - Read 32 Bytes 127 sub r12, r12, #32 128 cmp r12, #31 129 ldmia r14!, {r2-r9} 130 131 // If length is less than 32 then disable optim 132 movls r0, #0 133 134 cmp r12, #0 135 136 // Optimized memcopy - Write 32 Bytes 137 stmia r10!, {r2-r9} 138 139 // while (length != 0) 140 bne memcopy_default_loop 141 142 memcopy_end 143 mov r0, r11 144 ldmfd sp!, {r4-r11, pc} 145 146 END 147 148
