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https://github.com/italicsjenga/agb.git
synced 2024-12-24 00:31:34 +11:00
Update agbabi's memcpy
This commit is contained in:
Gwilym Kuiper
parent
6a8aeeb3e8
commit
a9da4a65f9
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@ -12,6 +12,7 @@ fn main() {
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println!("cargo:rerun-if-changed=gba.ld");
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println!("cargo:rerun-if-changed=gba_mb.ld");
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println!("cargo:rerun-if-changed=src/asm_include.s");
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println!("cargo:rerun-if-changed=src/agbabi/macros.inc");
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println!("cargo:rerun-if-changed=gfx/test_logo.png");
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println!("cargo:rerun-if-changed=build.rs");
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43
agb/src/agbabi/macros.inc
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43
agb/src/agbabi/macros.inc
Normal file
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@ -0,0 +1,43 @@
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/*
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===============================================================================
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ARM assembly support macros
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Copyright (C) 2021-2022 agbabi contributors
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For conditions of distribution and use, see copyright notice in LICENSE.md
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===============================================================================
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*/
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// Shift and test upper two bits, clobbering \reg
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// Use mi for first bit, cs for second bit
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.macro joaobapt_test_lsl reg shift = #0
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movs \reg, \reg, lsl \shift
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.endm
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// Test lowest two bits, clobbering \reg
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// Use mi for low bit, cs for high bit
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.macro joaobapt_test reg
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joaobapt_test_lsl \reg, #31
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.endm
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// Test lowest two bits of \src, result stored in \dst
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// Use mi for low bit, cs for high bit
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.macro joaobapt_test_into dst, src
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movs \dst, \src, lsl #31
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.endm
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// Branches depending on lowest two bits, clobbering \reg
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// b_mi = low bit case, b_cs = high bit case
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.macro joaobapt_switch reg, b_mi, b_cs
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joaobapt_test \reg
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bmi \b_mi
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bcs \b_cs
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.endm
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// Branches depending on alignment of \a and \b, clobbering \scratch
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// b_byte = off-by-byte case, b_half = off-by-half case
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.macro align_switch a, b, scratch, b_byte, b_half
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eor \scratch, \a, \b
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joaobapt_switch \scratch, \b_byte, \b_half
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.endm
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@ -1,19 +1,18 @@
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/*
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===============================================================================
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ABI:
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__aeabi_memcpy, __aeabi_memcpy4, __aeabi_memcpy8
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Standard:
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memcpy
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Support:
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__agbabi_memcpy2
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__agbabi_memcpy2, __agbabi_memcpy1
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Copyright (C) 2021-2022 agbabi contributors
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For conditions of distribution and use, see copyright notice in LICENSE.md
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===============================================================================
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*/
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.include "src/agbabi/macros.inc"
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.arm
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.align 2
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@ -22,95 +21,97 @@
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__agbabi_memcpy:
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.global __aeabi_memcpy
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__aeabi_memcpy:
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// Check pointer alignment
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eor r3, r1, r0
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// JoaoBapt carry & sign bit test
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movs r3, r3, lsl #31
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bmi .Lcopy1
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bcs .Lcopy2
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// >6-bytes is roughly the threshold when byte-by-byte copy is slower
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cmp r2, #6
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ble __agbabi_memcpy1
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.Lcopy4:
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// Handle <= 2 byte copies byte-by-byte
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cmp r2, #2
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ble .Lcopy1
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align_switch r0, r1, r3, __agbabi_memcpy1, .Lcopy_halves
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// Copy half and byte head
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rsb r3, r0, #4
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// JoaoBapt carry & sign bit test
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movs r3, r3, lsl #31
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// Check if r0 (or r1) needs word aligning
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rsbs r3, r0, #4
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joaobapt_test r3
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// Copy byte head to align
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ldrmib r3, [r1], #1
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strmib r3, [r0], #1
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submi r2, r2, #1
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// r0, r1 are now half aligned
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// Copy half head to align
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ldrcsh r3, [r1], #2
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strcsh r3, [r0], #2
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subcs r2, r2, #2
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// Fallthrough
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// r0, r1 are now word aligned
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.global __aeabi_memcpy8
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__aeabi_memcpy8:
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.global __aeabi_memcpy4
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__aeabi_memcpy4:
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// Copy 8 words
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movs r12, r2, lsr #5
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beq .Lskip32
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lsl r3, r12, #5
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sub r2, r2, r3
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cmp r2, #32
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blt .Lcopy_words
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// Word aligned, 32-byte copy
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push {r4-r10}
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.LcopyWords8:
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ldmia r1!, {r3-r10}
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stmia r0!, {r3-r10}
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subs r12, r12, #1
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bne .LcopyWords8
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.Lloop_32:
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subs r2, r2, #32
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ldmgeia r1!, {r3-r10}
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stmgeia r0!, {r3-r10}
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bgt .Lloop_32
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pop {r4-r10}
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.Lskip32:
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bxeq lr
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// Copy words
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movs r12, r2, lsr #2
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.LcopyWords:
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subs r12, r12, #1
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ldrhs r3, [r1], #4
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strhs r3, [r0], #4
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bhs .LcopyWords
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// < 32 bytes remaining to be copied
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add r2, r2, #32
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// Copy half and byte tail
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// JoaoBapt carry & sign bit test
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movs r3, r2, lsl #31
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.Lcopy_words:
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cmp r2, #4
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blt .Lcopy_halves
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.Lloop_4:
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subs r2, r2, #4
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ldrge r3, [r1], #4
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strge r3, [r0], #4
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bgt .Lloop_4
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bxeq lr
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// Copy byte & half tail
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// This test still works when r2 is negative
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joaobapt_test r2
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// Copy half
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ldrcsh r3, [r1], #2
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strcsh r3, [r0], #2
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// Copy byte
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ldrmib r3, [r1]
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strmib r3, [r0]
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bx lr
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.Lcopy2:
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// Copy byte head
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.Lcopy_halves:
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// Copy byte head to align
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tst r0, #1
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cmpne r2, #0
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ldrneb r3, [r1], #1
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strneb r3, [r0], #1
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subne r2, r2, #1
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// Fallthrough
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// r0, r1 are now half aligned
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.global __agbabi_memcpy2
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__agbabi_memcpy2:
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// Copy halves
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movs r12, r2, lsr #1
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.LcopyHalves:
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subs r12, r12, #1
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ldrhsh r3, [r1], #2
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strhsh r3, [r0], #2
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bhs .LcopyHalves
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subs r2, r2, #2
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ldrgeh r3, [r1], #2
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strgeh r3, [r0], #2
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bgt __agbabi_memcpy2
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bxeq lr
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// Copy byte tail
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tst r2, #1
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ldrneb r3, [r1]
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strneb r3, [r0]
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adds r2, r2, #1
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ldreqb r3, [r1]
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streqb r3, [r0]
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bx lr
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.Lcopy1:
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.global __agbabi_memcpy1
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__agbabi_memcpy1:
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subs r2, r2, #1
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ldrhsb r3, [r1], #1
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strhsb r3, [r0], #1
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bhs .Lcopy1
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ldrgeb r3, [r1], #1
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strgeb r3, [r0], #1
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bgt __agbabi_memcpy1
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bx lr
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.section .iwram.memcpy, "ax", %progbits
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