mirror of
https://github.com/CloverHackyColor/CloverBootloader.git
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142 lines
3.3 KiB
NASM
142 lines
3.3 KiB
NASM
;------------------------------------------------------------------------------
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;
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; CopyMem() worker for ARM
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;
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; This file started out as C code that did 64 bit moves if the buffer was
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; 32-bit aligned, else it does a byte copy. It also does a byte copy for
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; any trailing bytes. It was updated to do 32-byte copies using stm/ldm.
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;
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; Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
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; Copyright (c) 2016, Linaro Ltd. All rights reserved.<BR>
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; SPDX-License-Identifier: BSD-2-Clause-Patent
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;
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;------------------------------------------------------------------------------
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EXPORT InternalMemCopyMem
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AREA SetMem, CODE, READONLY
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THUMB
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InternalMemCopyMem
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stmfd sp!, {r4-r11, lr}
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// Save the input parameters in extra registers (r11 = destination, r14 = source, r12 = length)
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mov r11, r0
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mov r10, r0
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mov r12, r2
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mov r14, r1
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memcopy_check_overlapped
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cmp r11, r1
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// If (dest < source)
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bcc memcopy_check_optim_default
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// If (source + length < dest)
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rsb r3, r1, r11
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cmp r12, r3
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bcc memcopy_check_optim_default
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b memcopy_check_optim_overlap
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memcopy_check_optim_default
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// Check if we can use an optimized path ((length >= 32) && destination word-aligned && source word-aligned) for the memcopy (optimized path if r0 == 1)
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tst r0, #0xF
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movne r0, #0
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bne memcopy_default
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tst r1, #0xF
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movne r3, #0
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moveq r3, #1
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cmp r2, #31
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movls r0, #0
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andhi r0, r3, #1
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b memcopy_default
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memcopy_check_optim_overlap
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// r10 = dest_end, r14 = source_end
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add r10, r11, r12
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add r14, r12, r1
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// Are we in the optimized case ((length >= 32) && dest_end word-aligned && source_end word-aligned)
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cmp r2, #31
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movls r0, #0
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movhi r0, #1
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tst r10, #0xF
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movne r0, #0
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tst r14, #0xF
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movne r0, #0
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b memcopy_overlapped
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memcopy_overlapped_non_optim
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// We read 1 byte from the end of the source buffer
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sub r3, r14, #1
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sub r12, r12, #1
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ldrb r3, [r3, #0]
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sub r2, r10, #1
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cmp r12, #0
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// We write 1 byte at the end of the dest buffer
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sub r10, r10, #1
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sub r14, r14, #1
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strb r3, [r2, #0]
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bne memcopy_overlapped_non_optim
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b memcopy_end
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// r10 = dest_end, r14 = source_end
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memcopy_overlapped
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// Are we in the optimized case ?
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cmp r0, #0
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beq memcopy_overlapped_non_optim
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// Optimized Overlapped - Read 32 bytes
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sub r14, r14, #32
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sub r12, r12, #32
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cmp r12, #31
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ldmia r14, {r2-r9}
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// If length is less than 32 then disable optim
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movls r0, #0
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cmp r12, #0
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// Optimized Overlapped - Write 32 bytes
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sub r10, r10, #32
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stmia r10, {r2-r9}
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// while (length != 0)
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bne memcopy_overlapped
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b memcopy_end
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memcopy_default_non_optim
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// Byte copy
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ldrb r3, [r14], #1
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sub r12, r12, #1
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strb r3, [r10], #1
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memcopy_default
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cmp r12, #0
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beq memcopy_end
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// r10 = dest, r14 = source
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memcopy_default_loop
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cmp r0, #0
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beq memcopy_default_non_optim
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// Optimized memcopy - Read 32 Bytes
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sub r12, r12, #32
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cmp r12, #31
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ldmia r14!, {r2-r9}
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// If length is less than 32 then disable optim
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movls r0, #0
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cmp r12, #0
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// Optimized memcopy - Write 32 Bytes
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stmia r10!, {r2-r9}
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// while (length != 0)
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bne memcopy_default_loop
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memcopy_end
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mov r0, r11
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ldmfd sp!, {r4-r11, pc}
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END
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