+/*
+ * Copyright (c) 2006, 2009 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+/*****************************************************************************
+ * ARMv5 and ARMv6 implementation, also used in dyld on later archs *
+ *****************************************************************************/
+
+#include <arm/arch.h>
+#if !defined _ARM_ARCH_7 || defined VARIANT_DYLD
+
+.text
+.align 2
+
+ .globl _memcpy
+ .globl _bcopy
+ .globl _memmove
+
+_bcopy: /* void bcopy(const void *src, void *dest, size_t len); */
+ mov r3, r0
+ mov r0, r1
+ mov r1, r3
+
+_memcpy: /* void *memcpy(void *dest, const void *src, size_t len); */
+_memmove: /* void *memmove(void *dest, const void *src, size_t len); */
+ /* check for zero len or if the pointers are the same */
+ cmp r2, #0
+ cmpne r0, r1
+ bxeq lr
+
+ /* save r0 (return value), r4 (scratch), and r5 (scratch) */
+ stmfd sp!, { r0, r4, r5, r7, lr }
+ add r7, sp, #12
+
+ /* check for overlap. r3 <- distance between src & dest */
+ subhs r3, r0, r1
+ sublo r3, r1, r0
+ cmp r3, r2 /* if distance(src, dest) < len, we have overlap */
+ blo Loverlap
+
+Lnormalforwardcopy:
+ /* are src and dest dissimilarly word aligned? */
+ mov r12, r0, lsl #30
+ cmp r12, r1, lsl #30
+ bne Lnonwordaligned_forward
+
+ /* if len < 64, do a quick forward copy */
+ cmp r2, #64
+ blt Lsmallforwardcopy
+
+ /* check for 16 byte src/dest unalignment */
+ tst r0, #0xf
+ bne Lsimilarlyunaligned
+
+ /* check for 32 byte dest unalignment */
+ tst r0, #(1<<4)
+ bne Lunaligned_32
+
+Lmorethan64_aligned:
+ /* save some more registers to use in the copy */
+ stmfd sp!, { r6, r8, r10, r11 }
+
+ /* pre-subtract 64 from the len counter to avoid an extra compare in the loop */
+ sub r2, r2, #64
+
+L64loop:
+ /* copy 64 bytes at a time */
+ ldmia r1!, { r3, r4, r5, r6, r8, r10, r11, r12 }
+#ifdef _ARM_ARCH_6
+ pld [r1, #32]
+#endif
+ stmia r0!, { r3, r4, r5, r6, r8, r10, r11, r12 }
+ ldmia r1!, { r3, r4, r5, r6, r8, r10, r11, r12 }
+ subs r2, r2, #64
+#ifdef _ARM_ARCH_6
+ pld [r1, #32]
+#endif
+ stmia r0!, { r3, r4, r5, r6, r8, r10, r11, r12 }
+ bge L64loop
+
+ /* restore the scratch registers we just saved */
+ ldmfd sp!, { r6, r8, r10, r11 }
+
+ /* fix up the len counter (previously subtracted an extra 64 from it) and test for completion */
+ adds r2, r2, #64
+ beq Lexit
+
+Llessthan64_aligned:
+ /* copy 16 bytes at a time until we have < 16 bytes */
+ cmp r2, #16
+ ldmgeia r1!, { r3, r4, r5, r12 }
+ stmgeia r0!, { r3, r4, r5, r12 }
+ subges r2, r2, #16
+ bgt Llessthan64_aligned
+ beq Lexit
+
+Llessthan16_aligned:
+ mov r2, r2, lsl #28
+ msr cpsr_f, r2
+
+ ldmmiia r1!, { r2, r3 }
+ ldreq r4, [r1], #4
+ ldrcsh r5, [r1], #2
+ ldrvsb r12, [r1], #1
+
+ stmmiia r0!, { r2, r3 }
+ streq r4, [r0], #4
+ strcsh r5, [r0], #2
+ strvsb r12, [r0], #1
+ b Lexit
+
+Lsimilarlyunaligned:
+ /* both src and dest are unaligned in similar ways, align to dest on 32 byte boundary */
+ mov r12, r0, lsl #28
+ rsb r12, r12, #0
+ msr cpsr_f, r12
+
+ ldrvsb r3, [r1], #1
+ ldrcsh r4, [r1], #2
+ ldreq r5, [r1], #4
+
+ strvsb r3, [r0], #1
+ strcsh r4, [r0], #2
+ streq r5, [r0], #4
+
+ ldmmiia r1!, { r3, r4 }
+ stmmiia r0!, { r3, r4 }
+
+ subs r2, r2, r12, lsr #28
+ beq Lexit
+
+Lunaligned_32:
+ /* bring up to dest 32 byte alignment */
+ tst r0, #(1 << 4)
+ ldmneia r1!, { r3, r4, r5, r12 }
+ stmneia r0!, { r3, r4, r5, r12 }
+ subne r2, r2, #16
+
+ /* we should now be aligned, see what copy method we should use */
+ cmp r2, #64
+ bge Lmorethan64_aligned
+ b Llessthan64_aligned
+
+Lbytewise2:
+ /* copy 2 bytes at a time */
+ subs r2, r2, #2
+
+ ldrb r3, [r1], #1
+ ldrplb r4, [r1], #1
+
+ strb r3, [r0], #1
+ strplb r4, [r0], #1
+
+ bhi Lbytewise2
+ b Lexit
+
+Lbytewise:
+ /* simple bytewise forward copy */
+ ldrb r3, [r1], #1
+ subs r2, r2, #1
+ strb r3, [r0], #1
+ bne Lbytewise
+ b Lexit
+
+Lsmallforwardcopy:
+ /* src and dest are word aligned similarly, less than 64 bytes to copy */
+ cmp r2, #4
+ blt Lbytewise2
+
+ /* bytewise copy until word aligned */
+ tst r1, #3
+Lwordalignloop:
+ ldrneb r3, [r1], #1
+ strneb r3, [r0], #1
+ subne r2, r2, #1
+ tstne r1, #3
+ bne Lwordalignloop
+
+ cmp r2, #16
+ bge Llessthan64_aligned
+ blt Llessthan16_aligned
+
+Loverlap:
+ /* src and dest overlap in some way, len > 0 */
+ cmp r0, r1 /* if dest > src */
+ bhi Loverlap_srclower
+
+Loverlap_destlower:
+ /* dest < src, see if we can still do a fast forward copy or fallback to slow forward copy */
+ cmp r3, #64
+ bge Lnormalforwardcopy /* overlap is greater than one stride of the copy, use normal copy */
+
+ cmp r3, #2
+ bge Lbytewise2
+ b Lbytewise
+
+ /* the following routines deal with having to copy in the reverse direction */
+Loverlap_srclower:
+ /* src < dest, with overlap */
+
+ /* src += len; dest += len; */
+ add r0, r0, r2
+ add r1, r1, r2
+
+ /* we have to copy in reverse no matter what, test if we can we use a large block reverse copy */
+ cmp r2, #64 /* less than 64 bytes to copy? */
+ cmpgt r3, #64 /* less than 64 bytes of nonoverlap? */
+ blt Lbytewise_reverse
+
+ /* test of src and dest are nonword aligned differently */
+ mov r3, r0, lsl #30
+ cmp r3, r1, lsl #30
+ bne Lbytewise_reverse
+
+ /* test if src and dest are non word aligned or dest is non 16 byte aligned */
+ tst r0, #0xf
+ bne Lunaligned_reverse_similarly
+
+ /* test for dest 32 byte alignment */
+ tst r0, #(1<<4)
+ bne Lunaligned_32_reverse_similarly
+
+ /* 64 byte reverse block copy, src and dest aligned */
+Lmorethan64_aligned_reverse:
+ /* save some more registers to use in the copy */
+ stmfd sp!, { r6, r8, r10, r11 }
+
+ /* pre-subtract 64 from the len counter to avoid an extra compare in the loop */
+ sub r2, r2, #64
+
+L64loop_reverse:
+ /* copy 64 bytes at a time */
+ ldmdb r1!, { r3, r4, r5, r6, r8, r10, r11, r12 }
+#ifdef _ARM_ARCH_6
+ pld [r1, #-32]
+#endif
+ stmdb r0!, { r3, r4, r5, r6, r8, r10, r11, r12 }
+ ldmdb r1!, { r3, r4, r5, r6, r8, r10, r11, r12 }
+ subs r2, r2, #64
+#ifdef _ARM_ARCH_6
+ pld [r1, #-32]
+#endif
+ stmdb r0!, { r3, r4, r5, r6, r8, r10, r11, r12 }
+ bge L64loop_reverse
+
+ /* restore the scratch registers we just saved */
+ ldmfd sp!, { r6, r8, r10, r11 }
+
+ /* fix up the len counter (previously subtracted an extra 64 from it) and test for completion */
+ adds r2, r2, #64
+ beq Lexit
+
+Lbytewise_reverse:
+ ldrb r3, [r1, #-1]!
+ strb r3, [r0, #-1]!
+ subs r2, r2, #1
+ bne Lbytewise_reverse
+ b Lexit
+
+Lunaligned_reverse_similarly:
+ /* both src and dest are unaligned in similar ways, align to dest on 32 byte boundary */
+ mov r12, r0, lsl #28
+ msr cpsr_f, r12
+
+ ldrvsb r3, [r1, #-1]!
+ ldrcsh r4, [r1, #-2]!
+ ldreq r5, [r1, #-4]!
+
+ strvsb r3, [r0, #-1]!
+ strcsh r4, [r0, #-2]!
+ streq r5, [r0, #-4]!
+
+ ldmmidb r1!, { r3, r4 }
+ stmmidb r0!, { r3, r4 }
+
+ subs r2, r2, r12, lsr #28
+ beq Lexit
+
+Lunaligned_32_reverse_similarly:
+ /* bring up to dest 32 byte alignment */
+ tst r0, #(1 << 4)
+ ldmnedb r1!, { r3, r4, r5, r12 }
+ stmnedb r0!, { r3, r4, r5, r12 }
+ subne r2, r2, #16
+
+ /* we should now be aligned, see what copy method we should use */
+ cmp r2, #64
+ bge Lmorethan64_aligned_reverse
+ b Lbytewise_reverse
+
+ /* the following routines deal with non word aligned copies */
+Lnonwordaligned_forward:
+ cmp r2, #8
+ blt Lbytewise2 /* not worth the effort with less than 24 bytes total */
+
+ /* bytewise copy until src word aligned */
+ tst r1, #3
+Lwordalignloop2:
+ ldrneb r3, [r1], #1
+ strneb r3, [r0], #1
+ subne r2, r2, #1
+ tstne r1, #3
+ bne Lwordalignloop2
+
+ /* figure out how the src and dest are unaligned */
+ and r3, r0, #3
+ cmp r3, #2
+ blt Lalign1_forward
+ beq Lalign2_forward
+ bgt Lalign3_forward
+
+Lalign1_forward:
+ /* the dest pointer is 1 byte off from src */
+ mov r12, r2, lsr #2 /* number of words we should copy */
+ sub r0, r0, #1
+
+ /* prime the copy */
+ ldrb r4, [r0] /* load D[7:0] */
+
+Lalign1_forward_loop:
+ ldr r3, [r1], #4 /* load S */
+ orr r4, r4, r3, lsl #8 /* D[31:8] = S[24:0] */
+ str r4, [r0], #4 /* save D */
+ mov r4, r3, lsr #24 /* D[7:0] = S[31:25] */
+ subs r12, r12, #1
+ bne Lalign1_forward_loop
+
+ /* finish the copy off */
+ strb r4, [r0], #1 /* save D[7:0] */
+
+ ands r2, r2, #3
+ beq Lexit
+ b Lbytewise2
+
+Lalign2_forward:
+ /* the dest pointer is 2 bytes off from src */
+ mov r12, r2, lsr #2 /* number of words we should copy */
+ sub r0, r0, #2
+
+ /* prime the copy */
+ ldrh r4, [r0] /* load D[15:0] */
+
+Lalign2_forward_loop:
+ ldr r3, [r1], #4 /* load S */
+ orr r4, r4, r3, lsl #16 /* D[31:16] = S[15:0] */
+ str r4, [r0], #4 /* save D */
+ mov r4, r3, lsr #16 /* D[15:0] = S[31:15] */
+ subs r12, r12, #1
+ bne Lalign2_forward_loop
+
+ /* finish the copy off */
+ strh r4, [r0], #2 /* save D[15:0] */
+
+ ands r2, r2, #3
+ beq Lexit
+ b Lbytewise2
+
+Lalign3_forward:
+ /* the dest pointer is 3 bytes off from src */
+ mov r12, r2, lsr #2 /* number of words we should copy */
+ sub r0, r0, #3
+
+ /* prime the copy */
+ ldr r4, [r0]
+ and r4, r4, #0x00ffffff /* load D[24:0] */
+
+Lalign3_forward_loop:
+ ldr r3, [r1], #4 /* load S */
+ orr r4, r4, r3, lsl #24 /* D[31:25] = S[7:0] */
+ str r4, [r0], #4 /* save D */
+ mov r4, r3, lsr #8 /* D[24:0] = S[31:8] */
+ subs r12, r12, #1
+ bne Lalign3_forward_loop
+
+ /* finish the copy off */
+ strh r4, [r0], #2 /* save D[15:0] */
+ mov r4, r4, lsr #16
+ strb r4, [r0], #1 /* save D[23:16] */
+
+ ands r2, r2, #3
+ beq Lexit
+ b Lbytewise2
+
+Lexit:
+ ldmfd sp!, {r0, r4, r5, r7, pc}
+
+#endif // !defined _ARM_ARCH_7 || defined VARIANT_DYLD
+
projects / apple / libc.git / blobdiff