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-rw-r--r--libc/string/arm/_memcpy.S182
1 files changed, 168 insertions, 14 deletions
diff --git a/libc/string/arm/_memcpy.S b/libc/string/arm/_memcpy.S
index 3704f96b5..5ef63c45a 100644
--- a/libc/string/arm/_memcpy.S
+++ b/libc/string/arm/_memcpy.S
@@ -39,7 +39,9 @@
#include <features.h>
#include <endian.h>
+#include <bits/arm_asm.h>
+#if !defined(THUMB1_ONLY)
/*
* This is one fun bit of code ...
* Some easy listening music is suggested while trying to understand this
@@ -77,11 +79,36 @@
.type _memcpy,%function
.align 4
+/* XXX: The Thumb-2 conditionals can be removed if/when we require an
+ assembler that supports unified syntax. */
+.macro copy regs
+#if defined(__thumb2__)
+ ittt ge
+ ldmiage r1!, \regs
+ stmiage r0!, \regs
+#else
+ ldmgeia r1!, \regs
+ stmgeia r0!, \regs
+#endif
+.endm
+
+.macro copydb regs
+#if defined(__thumb2__)
+ ittt ge
+ ldmdbge r1!, \regs
+ stmdbge r0!, \regs
+#else
+ ldmgedb r1!, \regs
+ stmgedb r0!, \regs
+#endif
+.endm
+
_memcpy:
/* Determine copy direction */
cmp r1, r0
bcc .Lmemcpy_backwards
+ IT(tt, eq)
moveq r0, #0 /* Quick abort for len=0 */
#if defined(__USE_BX__)
bxeq lr
@@ -102,7 +129,7 @@ _memcpy:
blt .Lmemcpy_fl12 /* less than 12 bytes (4 from above) */
subs r2, r2, #0x14
blt .Lmemcpy_fl32 /* less than 32 bytes (12 from above) */
- stmdb sp!, {r4} /* borrow r4 */
+ str r4, [sp, #-4]! /* borrow r4 */
/* blat 32 bytes at a time */
/* XXX for really big copies perhaps we should use more registers */
@@ -115,19 +142,22 @@ _memcpy:
bge .Lmemcpy_floop32
cmn r2, #0x10
- ldmgeia r1!, {r3, r4, r12, lr} /* blat a remaining 16 bytes */
- stmgeia r0!, {r3, r4, r12, lr}
+ /* blat a remaining 16 bytes */
+ copy "{r3, r4, r12, lr}"
subge r2, r2, #0x10
- ldmia sp!, {r4} /* return r4 */
+ ldr r4, [sp], #4 /* restore r4 */
.Lmemcpy_fl32:
adds r2, r2, #0x14
/* blat 12 bytes at a time */
.Lmemcpy_floop12:
- ldmgeia r1!, {r3, r12, lr}
- stmgeia r0!, {r3, r12, lr}
+ copy "{r3, r12, lr}"
+#if defined(__thumb2__)
+ subsge r2, r2, #0x0c
+#else
subges r2, r2, #0x0c
+#endif
bge .Lmemcpy_floop12
.Lmemcpy_fl12:
@@ -135,26 +165,48 @@ _memcpy:
blt .Lmemcpy_fl4
subs r2, r2, #4
+ IT(tt, lt)
ldrlt r3, [r1], #4
strlt r3, [r0], #4
- ldmgeia r1!, {r3, r12}
- stmgeia r0!, {r3, r12}
+ copy "{r3, r12}"
subge r2, r2, #4
.Lmemcpy_fl4:
/* less than 4 bytes to go */
adds r2, r2, #4
+#if defined(__thumb2__)
+ it eq
+ popeq {r0, pc} /* done */
+#elif defined(__ARM_ARCH_4T__)
+ ldmeqia sp!, {r0, r3} /* done */
+ bxeq r3
+#else
ldmeqia sp!, {r0, pc} /* done */
+#endif
/* copy the crud byte at a time */
cmp r2, #2
ldrb r3, [r1], #1
strb r3, [r0], #1
+#if defined(__thumb2__)
+ itt ge
+ ldrbge r3, [r1], #1
+ strbge r3, [r0], #1
+ itt gt
+ ldrbgt r3, [r1], #1
+ strbgt r3, [r0], #1
+#else
ldrgeb r3, [r1], #1
strgeb r3, [r0], #1
ldrgtb r3, [r1], #1
strgtb r3, [r0], #1
+#endif
+#if defined(__ARM_ARCH_4T__)
+ ldmia sp!, {r0, r3}
+ bx r3
+#else
ldmia sp!, {r0, pc}
+#endif
/* erg - unaligned destination */
.Lmemcpy_fdestul:
@@ -164,10 +216,19 @@ _memcpy:
/* align destination with byte copies */
ldrb r3, [r1], #1
strb r3, [r0], #1
+#if defined(__thumb2__)
+ itt ge
+ ldrbge r3, [r1], #1
+ strbge r3, [r0], #1
+ itt gt
+ ldrbgt r3, [r1], #1
+ strbgt r3, [r0], #1
+#else
ldrgeb r3, [r1], #1
strgeb r3, [r0], #1
ldrgtb r3, [r1], #1
strgtb r3, [r0], #1
+#endif
subs r2, r2, r12
blt .Lmemcpy_fl4 /* less the 4 bytes */
@@ -370,12 +431,12 @@ _memcpy:
.Lmemcpy_bl32:
cmn r2, #0x10
- ldmgedb r1!, {r3, r4, r12, lr} /* blat a remaining 16 bytes */
- stmgedb r0!, {r3, r4, r12, lr}
+ /* blat a remaining 16 bytes */
+ copydb "{r3, r4, r12, lr}"
subge r2, r2, #0x10
adds r2, r2, #0x14
- ldmgedb r1!, {r3, r12, lr} /* blat a remaining 12 bytes */
- stmgedb r0!, {r3, r12, lr}
+ /* blat a remaining 12 bytes */
+ copydb "{r3, r12, lr}"
subge r2, r2, #0x0c
ldmia sp!, {r4, lr}
@@ -383,15 +444,16 @@ _memcpy:
adds r2, r2, #8
blt .Lmemcpy_bl4
subs r2, r2, #4
+ IT(tt, lt)
ldrlt r3, [r1, #-4]!
strlt r3, [r0, #-4]!
- ldmgedb r1!, {r3, r12}
- stmgedb r0!, {r3, r12}
+ copydb "{r3, r12}"
subge r2, r2, #4
.Lmemcpy_bl4:
/* less than 4 bytes to go */
adds r2, r2, #4
+ IT(t, eq)
#if defined(__USE_BX__)
bxeq lr
#else
@@ -401,10 +463,19 @@ _memcpy:
cmp r2, #2
ldrb r3, [r1, #-1]!
strb r3, [r0, #-1]!
+#ifdef __thumb2__
+ itt ge
+ ldrbge r3, [r1, #-1]!
+ strbge r3, [r0, #-1]!
+ itt gt
+ ldrbgt r3, [r1, #-1]!
+ strbgt r3, [r0, #-1]!
+#else
ldrgeb r3, [r1, #-1]!
strgeb r3, [r0, #-1]!
ldrgtb r3, [r1, #-1]!
strgtb r3, [r0, #-1]!
+#endif
#if defined(__USE_BX__)
bx lr
#else
@@ -417,10 +488,19 @@ _memcpy:
/* align destination with byte copies */
ldrb r3, [r1, #-1]!
strb r3, [r0, #-1]!
+#ifdef __thumb2__
+ itt ge
+ ldrbge r3, [r1, #-1]!
+ strbge r3, [r0, #-1]!
+ itt gt
+ ldrbgt r3, [r1, #-1]!
+ strbgt r3, [r0, #-1]!
+#else
ldrgeb r3, [r1, #-1]!
strgeb r3, [r0, #-1]!
ldrgtb r3, [r1, #-1]!
strgtb r3, [r0, #-1]!
+#endif
subs r2, r2, r12
blt .Lmemcpy_bl4 /* less than 4 bytes to go */
ands r12, r1, #3
@@ -591,3 +671,77 @@ _memcpy:
.Lmemcpy_bsrcul1l4:
add r1, r1, #1
b .Lmemcpy_bl4
+
+#else /* THUMB1_ONLY */
+
+/* This is a fairly dumb implementation for when we can't use the 32-bit code
+ above. */
+.text
+.global _memcpy
+.hidden _memcpy
+.type _memcpy,%function
+.align 4
+.thumb
+_memcpy:
+ push {r0, r4}
+ cmp r2, #0
+ beq .Lmemcpy_exit
+ @ See if we have overlapping regions, and need to reverse the
+ @ direction of the copy
+ cmp r0, r1
+ bls .Lmemcpy_forwards
+ add r4, r1, r2
+ cmp r0, r4
+ bcc .Lmemcpy_backwards
+.Lmemcpy_forwards:
+ /* Forwards. */
+ mov r3, r0
+ eor r3, r1
+ mov r4, #3
+ tst r3, r4
+ bne .Lmemcpy_funaligned
+ cmp r2, #8
+ bcc .Lmemcpy_funaligned
+1: @ copy up to the first word boundary.
+ tst r0, r4
+ beq 1f
+ ldrb r3, [r1]
+ add r1, r1, #1
+ strb r3, [r0]
+ add r0, r0, #1
+ sub r2, r2, #1
+ b 1b
+1: @ Copy aligned words
+ ldr r3, [r1]
+ add r1, r1, #4
+ str r3, [r0]
+ add r0, r0, #4
+ sub r2, r2, #4
+ cmp r2, #4
+ bcs 1b
+ cmp r2, #0
+ beq .Lmemcpy_exit
+.Lmemcpy_funaligned:
+1:
+ ldrb r3, [r1]
+ add r1, r1, #1
+ strb r3, [r0]
+ add r0, r0, #1
+ sub r2, r2, #1
+ bne 1b
+.Lmemcpy_exit:
+ pop {r0, r4}
+ bx lr
+
+.Lmemcpy_backwards:
+ add r0, r0, r2
+ add r1, r1, r2
+1:
+ sub r0, r0, #1
+ sub r1, r1, #1
+ ldrb r3, [r1]
+ strb r3, [r0]
+ sub r2, r2, #1
+ bne 1b
+ b .Lmemcpy_exit
+#endif
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-12 08:20:24 +0000