Initial commit

common/ndsabi/memcpy.s

@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: Zlib
+// SPDX-FileNotice: Modified from the original version by the BlocksDS project.
+//
+// Copyright (C) 2021-2023 agbabi contributors
+//
+// ABI:
+//    __aeabi_memcpy, __aeabi_memcpy4, __aeabi_memcpy8
+// Standard:
+//    memcpy
+// Support:
+//    __ndsabi_memcpy2, __ndsabi_memcpy1
+
+#include <nds/asminc.h>
+
+#include "macros.inc"
+
+    .syntax unified
+
+    .arm
+
+
+
+BEGIN_ASM_FUNC __aeabi_memcpy
+
+    @ >6-bytes is roughly the threshold when byte-by-byte copy is slower
+    cmp     r2, #6
+    ble     __ndsabi_memcpy1
+
+    align_switch r0, r1, r3, __ndsabi_memcpy1, .Lcopy_halves
+
+    @ Check if r0 (or r1) needs word aligning
+    rsbs    r3, r0, #4
+    joaobapt_test r3
+
+    @ Copy byte head to align
+    ldrbmi  r3, [r1], #1
+    strbmi  r3, [r0], #1
+    submi   r2, r2, #1
+    @ r0, r1 are now half aligned
+
+    @ Copy half head to align
+    ldrhcs  r3, [r1], #2
+    strhcs  r3, [r0], #2
+    subcs   r2, r2, #2
+    @ r0, r1 are now word aligned
+
+
+BEGIN_ASM_FUNC_NO_SECTION __aeabi_memcpy8
+BEGIN_ASM_FUNC_NO_SECTION __aeabi_memcpy4
+
+    cmp     r2, #32
+    blt     .Lcopy_words
+
+    @ Word aligned, 32-byte copy
+    push    {r4-r10}
+.Lloop_32:
+    subs    r2, r2, #32
+    ldmiage r1!, {r3-r10}
+    stmiage r0!, {r3-r10}
+    bgt     .Lloop_32
+    pop     {r4-r10}
+    bxeq    lr
+
+    @ < 32 bytes remaining to be copied
+    add     r2, r2, #32
+
+.Lcopy_words:
+    cmp     r2, #4
+    blt     .Lcopy_halves
+.Lloop_4:
+    subs    r2, r2, #4
+    ldrge   r3, [r1], #4
+    strge   r3, [r0], #4
+    bgt     .Lloop_4
+    bxeq    lr
+
+    @ Copy byte & half tail
+    @ This test still works when r2 is negative
+    joaobapt_test r2
+    @ Copy half
+    ldrhcs  r3, [r1], #2
+    strhcs  r3, [r0], #2
+    @ Copy byte
+    ldrbmi  r3, [r1]
+    strbmi  r3, [r0]
+    bx      lr
+
+.Lcopy_halves:
+    @ Copy byte head to align
+    tst     r0, #1
+    ldrbne  r3, [r1], #1
+    strbne  r3, [r0], #1
+    subne   r2, r2, #1
+    @ r0, r1 are now half aligned
+
+
+BEGIN_ASM_FUNC_NO_SECTION __ndsabi_memcpy2
+
+    subs    r2, r2, #2
+    ldrhge  r3, [r1], #2
+    strhge  r3, [r0], #2
+    bgt     __ndsabi_memcpy2
+    bxeq    lr
+
+    @ Copy byte tail
+    adds    r2, r2, #2
+    ldrbne  r3, [r1]
+    strbne  r3, [r0]
+    bx      lr
+
+
+BEGIN_ASM_FUNC __ndsabi_memcpy1
+
+    subs    r2, r2, #1
+    ldrbge  r3, [r1], #1
+    strbge  r3, [r0], #1
+    bgt     __ndsabi_memcpy1
+    bx      lr
+
+
+BEGIN_ASM_FUNC memcpy
+
+    push    {r0, lr}
+    bl      __aeabi_memcpy
+    pop     {r0, lr}
+    bx      lr