diff options
Diffstat (limited to 'Core/MdePkg/Library/BaseMemoryLibOptDxe/Arm/CopyMem.asm')
| -rw-r--r-- | Core/MdePkg/Library/BaseMemoryLibOptDxe/Arm/CopyMem.asm | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/Core/MdePkg/Library/BaseMemoryLibOptDxe/Arm/CopyMem.asm b/Core/MdePkg/Library/BaseMemoryLibOptDxe/Arm/CopyMem.asm new file mode 100644 index 0000000000..2034807954 --- /dev/null +++ b/Core/MdePkg/Library/BaseMemoryLibOptDxe/Arm/CopyMem.asm @@ -0,0 +1,147 @@ +;------------------------------------------------------------------------------
+;
+; 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>
+; Copyright (c) 2016, Linaro Ltd. 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.
+;
+;------------------------------------------------------------------------------
+
+ EXPORT InternalMemCopyMem
+ AREA SetMem, CODE, READONLY
+ THUMB
+
+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 (source + length < dest)
+ rsb r3, r1, r11
+ cmp r12, r3
+ bcc memcopy_check_optim_default
+ 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
+
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