/* * Copyright (c) 2006 Apple Computer, Inc. All rights reserved. * * @APPLE_OSREFERENCE_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. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * 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_OSREFERENCE_LICENSE_HEADER_END@ */ #include #include /* * The bcopy/memcpy loops, tuned for Pentium-M class processors with * Supplemental SSE3 and 64-byte cache lines. * * The following #defines are tightly coupled to the u-architecture: */ #define kShort 80 // too short to bother with SSE (must be >=80) #define kVeryLong (500*1024) // large enough for non-temporal stores (must be >= 8192) #define kFastUCode ((16*1024)-15) // cutoff for microcode fastpath for "rep/movsl" // void bcopy(const void *src, void *dst, size_t len); .text .align 5, 0x90 LZero: Lbcopy_sse3x: // void bcopy(const void *src, void *dst, size_t len) pushl %ebp // set up a frame for backtraces movl %esp,%ebp pushl %esi pushl %edi movl 8(%ebp),%esi // get source ptr movl 12(%ebp),%edi // get dest ptr movl 16(%ebp),%ecx // get length movl %edi,%edx subl %esi,%edx // (dest - source) cmpl %ecx,%edx // must move in reverse if (dest - source) < length jb LReverseIsland cmpl $(kShort),%ecx // long enough to bother with SSE? jbe Lshort // no jmp LNotShort // // void *memcpy(void *dst, const void *src, size_t len); // void *memmove(void *dst, const void *src, size_t len); // // NB: These need to be 32 bytes from bcopy(): // .align 5, 0x90 Lmemcpy: // void *memcpy(void *dst, const void *src, size_t len) Lmemmove: // void *memmove(void *dst, const void *src, size_t len) pushl %ebp // set up a frame for backtraces movl %esp,%ebp pushl %esi pushl %edi movl 8(%ebp),%edi // get dest ptr movl 12(%ebp),%esi // get source ptr movl 16(%ebp),%ecx // get length movl %edi,%edx subl %esi,%edx // (dest - source) cmpl %ecx,%edx // must move in reverse if (dest - source) < length jb LReverseIsland cmpl $(kShort),%ecx // long enough to bother with SSE? ja LNotShort // yes // Handle short forward copies. As the most common case, this is the fall-through path. // ecx = length (<= kShort) // esi = source ptr // edi = dest ptr Lshort: movl %ecx,%edx // copy length shrl $2,%ecx // get #doublewords jz LLeftovers 2: // loop copying doublewords movl (%esi),%eax addl $4,%esi movl %eax,(%edi) addl $4,%edi dec %ecx jnz 2b LLeftovers: // handle leftover bytes (0..3) in last word andl $3,%edx // any leftover bytes? jz Lexit 4: // loop copying bytes movb (%esi),%al inc %esi movb %al,(%edi) inc %edi dec %edx jnz 4b Lexit: movl 8(%ebp),%eax // get return value (dst ptr) for memcpy/memmove popl %edi popl %esi popl %ebp ret LReverseIsland: // keep the "jb" above a short branch... jmp LReverse // ...because reverse moves are uncommon // Handle forward moves that are long enough to justify use of SSE3. // First, 16-byte align the destination. // ecx = length (> kShort) // esi = source ptr // edi = dest ptr LNotShort: cmpl $(kVeryLong),%ecx // long enough to justify heavyweight loops? movl %edi,%edx // copy destination jae LVeryLong // use very-long-operand path negl %edx andl $15,%edx // get #bytes to align destination jz LDestAligned // already aligned subl %edx,%ecx // decrement length 1: // loop copying 1..15 bytes movb (%esi),%al inc %esi movb %al,(%edi) inc %edi dec %edx jnz 1b // Destination is now aligned. Dispatch to one of sixteen loops over 64-byte chunks, // based on the alignment of the source. All vector loads and stores are aligned. // Even though this means we have to shift and repack vectors, doing so is much faster // than unaligned loads. Since kShort>=80 and we've moved at most 15 bytes already, // there is at least one chunk. When we enter the copy loops, the following registers // are set up: // ecx = residual length (0..63) // edx = -(length to move), a multiple of 64 // esi = ptr to 1st source byte not to move (unaligned) // edi = ptr to 1st dest byte not to move (aligned) LDestAligned: movl %ecx,%edx // copy length movl %esi,%eax // copy source address andl $63,%ecx // get remaining bytes for Lshort andl $-64,%edx // get number of bytes we will copy in inner loop andl $15,%eax // mask to low 4 bits of source address addl %edx,%esi // point to 1st byte not copied addl %edx,%edi negl %edx // now generate offset to 1st byte to be copied movl (_COMM_PAGE_BCOPY+LTable-LZero)(,%eax,4),%eax jmp *%eax .align 2 LTable: // table of copy loop addresses .long LMod0 + _COMM_PAGE_BCOPY - LZero .long LMod1 + _COMM_PAGE_BCOPY - LZero .long LMod2 + _COMM_PAGE_BCOPY - LZero .long LMod3 + _COMM_PAGE_BCOPY - LZero .long LMod4 + _COMM_PAGE_BCOPY - LZero .long LMod5 + _COMM_PAGE_BCOPY - LZero .long LMod6 + _COMM_PAGE_BCOPY - LZero .long LMod7 + _COMM_PAGE_BCOPY - LZero .long LMod8 + _COMM_PAGE_BCOPY - LZero .long LMod9 + _COMM_PAGE_BCOPY - LZero .long LMod10 + _COMM_PAGE_BCOPY - LZero .long LMod11 + _COMM_PAGE_BCOPY - LZero .long LMod12 + _COMM_PAGE_BCOPY - LZero .long LMod13 + _COMM_PAGE_BCOPY - LZero .long LMod14 + _COMM_PAGE_BCOPY - LZero .long LMod15 + _COMM_PAGE_BCOPY - LZero // Very long forward moves. These are at least several pages. They are special cased // and aggressively optimized, not so much because they are common or useful, but // because they are subject to benchmark. There isn't enough room for them in the // area reserved on the commpage for bcopy, so we put them elsewhere. We call // the longcopy routine using the normal ABI. LVeryLong: pushl %ecx // length (>= kVeryLong) pushl %esi // source ptr pushl %edi // dest ptr movl $(_COMM_PAGE_LONGCOPY),%eax call *%eax // do the long copy addl $12,%esp // pop off our parameters jmp Lexit // On Pentium-M, the microcode for "rep/movsl" is faster than SSE for 8-byte // aligned operands from about 32KB up to kVeryLong for the hot cache case, and from // about 256 bytes up to kVeryLong for cold caches. This is because the microcode // avoids having to read destination cache lines that will be completely overwritten. // The cutoff we use (ie, kFastUCode) must somehow balance the two cases, since // we do not know if the destination is in cache or not. Lfastpath: addl %edx,%esi // restore ptrs to 1st byte of source and dest addl %edx,%edi negl %edx // make length positive orl %edx,%ecx // restore total #bytes remaining to move cld // we'll move forward movl %ecx,%edx // copy total length to move shrl $2,%ecx // compute #words to move rep // the u-code will optimize this movsl jmp LLeftovers // handle 0..3 leftover bytes // Forward loop for medium length operands in which low four bits of %esi == 0000 LMod0: cmpl $(-kFastUCode),%edx // %edx == -length, where (length < kVeryLong) jle Lfastpath // long enough for fastpath in microcode jmp 1f .align 4,0x90 // 16-byte align inner loops 1: // loop over 64-byte chunks movdqa (%esi,%edx),%xmm0 movdqa 16(%esi,%edx),%xmm1 movdqa 32(%esi,%edx),%xmm2 movdqa 48(%esi,%edx),%xmm3 movdqa %xmm0,(%edi,%edx) movdqa %xmm1,16(%edi,%edx) movdqa %xmm2,32(%edi,%edx) movdqa %xmm3,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 0001 LMod1: movdqa -1(%esi,%edx),%xmm0 // prime the loop by loading 1st quadword 1: // loop over 64-byte chunks movdqa 15(%esi,%edx),%xmm1 movdqa 31(%esi,%edx),%xmm2 movdqa 47(%esi,%edx),%xmm3 movdqa 63(%esi,%edx),%xmm4 movdqa %xmm0,%xmm5 movdqa %xmm4,%xmm0 palignr $1,%xmm3,%xmm4 // dest <- shr( dest || source, imm*8 ) palignr $1,%xmm2,%xmm3 palignr $1,%xmm1,%xmm2 palignr $1,%xmm5,%xmm1 movdqa %xmm1,(%edi,%edx) movdqa %xmm2,16(%edi,%edx) movdqa %xmm3,32(%edi,%edx) movdqa %xmm4,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 0010 LMod2: movdqa -2(%esi,%edx),%xmm0 // prime the loop by loading 1st source dq 1: // loop over 64-byte chunks movdqa 14(%esi,%edx),%xmm1 movdqa 30(%esi,%edx),%xmm2 movdqa 46(%esi,%edx),%xmm3 movdqa 62(%esi,%edx),%xmm4 movdqa %xmm0,%xmm5 movdqa %xmm4,%xmm0 palignr $2,%xmm3,%xmm4 // dest <- shr( dest || source, imm*8 ) palignr $2,%xmm2,%xmm3 palignr $2,%xmm1,%xmm2 palignr $2,%xmm5,%xmm1 movdqa %xmm1,(%edi,%edx) movdqa %xmm2,16(%edi,%edx) movdqa %xmm3,32(%edi,%edx) movdqa %xmm4,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 0011 LMod3: movdqa -3(%esi,%edx),%xmm0 // prime the loop by loading 1st source dq 1: // loop over 64-byte chunks movdqa 13(%esi,%edx),%xmm1 movdqa 29(%esi,%edx),%xmm2 movdqa 45(%esi,%edx),%xmm3 movdqa 61(%esi,%edx),%xmm4 movdqa %xmm0,%xmm5 movdqa %xmm4,%xmm0 palignr $3,%xmm3,%xmm4 // dest <- shr( dest || source, imm*8 ) palignr $3,%xmm2,%xmm3 palignr $3,%xmm1,%xmm2 palignr $3,%xmm5,%xmm1 movdqa %xmm1,(%edi,%edx) movdqa %xmm2,16(%edi,%edx) movdqa %xmm3,32(%edi,%edx) movdqa %xmm4,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 0100 // We use the float single data type in order to use "movss" to merge vectors. LMod4: movaps -4(%esi,%edx),%xmm0 // 4-byte aligned: prime the loop jmp 1f .align 4,0x90 1: // loop over 64-byte chunks movaps 12(%esi,%edx),%xmm1 movaps 28(%esi,%edx),%xmm2 movss %xmm1,%xmm0 // copy low 4 bytes of source into destination pshufd $(0x39),%xmm0,%xmm0 // rotate right 4 bytes (mask -- 00 11 10 01) movaps 44(%esi,%edx),%xmm3 movss %xmm2,%xmm1 pshufd $(0x39),%xmm1,%xmm1 movaps 60(%esi,%edx),%xmm4 movss %xmm3,%xmm2 pshufd $(0x39),%xmm2,%xmm2 movaps %xmm0,(%edi,%edx) movss %xmm4,%xmm3 pshufd $(0x39),%xmm3,%xmm3 movaps %xmm1,16(%edi,%edx) movaps %xmm2,32(%edi,%edx) movaps %xmm4,%xmm0 movaps %xmm3,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 0101 LMod5: movdqa -5(%esi,%edx),%xmm0 // prime the loop by loading 1st source dq 1: // loop over 64-byte chunks movdqa 11(%esi,%edx),%xmm1 movdqa 27(%esi,%edx),%xmm2 movdqa 43(%esi,%edx),%xmm3 movdqa 59(%esi,%edx),%xmm4 movdqa %xmm0,%xmm5 movdqa %xmm4,%xmm0 palignr $5,%xmm3,%xmm4 // dest <- shr( dest || source, imm*8 ) palignr $5,%xmm2,%xmm3 palignr $5,%xmm1,%xmm2 palignr $5,%xmm5,%xmm1 movdqa %xmm1,(%edi,%edx) movdqa %xmm2,16(%edi,%edx) movdqa %xmm3,32(%edi,%edx) movdqa %xmm4,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 0110 LMod6: movdqa -6(%esi,%edx),%xmm0 // prime the loop by loading 1st source dq 1: // loop over 64-byte chunks movdqa 10(%esi,%edx),%xmm1 movdqa 26(%esi,%edx),%xmm2 movdqa 42(%esi,%edx),%xmm3 movdqa 58(%esi,%edx),%xmm4 movdqa %xmm0,%xmm5 movdqa %xmm4,%xmm0 palignr $6,%xmm3,%xmm4 // dest <- shr( dest || source, imm*8 ) palignr $6,%xmm2,%xmm3 palignr $6,%xmm1,%xmm2 palignr $6,%xmm5,%xmm1 movdqa %xmm1,(%edi,%edx) movdqa %xmm2,16(%edi,%edx) movdqa %xmm3,32(%edi,%edx) movdqa %xmm4,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 0111 LMod7: movdqa -7(%esi,%edx),%xmm0 // prime the loop by loading 1st source dq 1: // loop over 64-byte chunks movdqa 9(%esi,%edx),%xmm1 movdqa 25(%esi,%edx),%xmm2 movdqa 41(%esi,%edx),%xmm3 movdqa 57(%esi,%edx),%xmm4 movdqa %xmm0,%xmm5 movdqa %xmm4,%xmm0 palignr $7,%xmm3,%xmm4 // dest <- shr( dest || source, imm*8 ) palignr $7,%xmm2,%xmm3 palignr $7,%xmm1,%xmm2 palignr $7,%xmm5,%xmm1 movdqa %xmm1,(%edi,%edx) movdqa %xmm2,16(%edi,%edx) movdqa %xmm3,32(%edi,%edx) movdqa %xmm4,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 1000 // We use the float double data type in order to use "shufpd" to shift by 8 bytes. LMod8: cmpl $(-kFastUCode),%edx // %edx == -length, where (length < kVeryLong) jle Lfastpath // long enough for fastpath in microcode movapd -8(%esi,%edx),%xmm0 // 8-byte aligned: prime the loop jmp 1f .align 4,0x90 1: // loop over 64-byte chunks movapd 8(%esi,%edx),%xmm1 movapd 24(%esi,%edx),%xmm2 shufpd $01,%xmm1,%xmm0 // %xmm0 <- shr( %xmm0 || %xmm1, 8 bytes) movapd 40(%esi,%edx),%xmm3 shufpd $01,%xmm2,%xmm1 movapd 56(%esi,%edx),%xmm4 shufpd $01,%xmm3,%xmm2 movapd %xmm0,(%edi,%edx) shufpd $01,%xmm4,%xmm3 movapd %xmm1,16(%edi,%edx) movapd %xmm2,32(%edi,%edx) movapd %xmm4,%xmm0 movapd %xmm3,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 1001 LMod9: movdqa -9(%esi,%edx),%xmm0 // prime the loop by loading 1st source dq 1: // loop over 64-byte chunks movdqa 7(%esi,%edx),%xmm1 movdqa 23(%esi,%edx),%xmm2 movdqa 39(%esi,%edx),%xmm3 movdqa 55(%esi,%edx),%xmm4 movdqa %xmm0,%xmm5 movdqa %xmm4,%xmm0 palignr $9,%xmm3,%xmm4 // dest <- shr( dest || source, imm*8 ) palignr $9,%xmm2,%xmm3 palignr $9,%xmm1,%xmm2 palignr $9,%xmm5,%xmm1 movdqa %xmm1,(%edi,%edx) movdqa %xmm2,16(%edi,%edx) movdqa %xmm3,32(%edi,%edx) movdqa %xmm4,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 1010 LMod10: movdqa -10(%esi,%edx),%xmm0 // prime the loop by loading 1st source dq 1: // loop over 64-byte chunks movdqa 6(%esi,%edx),%xmm1 movdqa 22(%esi,%edx),%xmm2 movdqa 38(%esi,%edx),%xmm3 movdqa 54(%esi,%edx),%xmm4 movdqa %xmm0,%xmm5 movdqa %xmm4,%xmm0 palignr $10,%xmm3,%xmm4 // dest <- shr( dest || source, imm*8 ) palignr $10,%xmm2,%xmm3 palignr $10,%xmm1,%xmm2 palignr $10,%xmm5,%xmm1 movdqa %xmm1,(%edi,%edx) movdqa %xmm2,16(%edi,%edx) movdqa %xmm3,32(%edi,%edx) movdqa %xmm4,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 1011 LMod11: movdqa -11(%esi,%edx),%xmm0 // prime the loop by loading 1st source dq 1: // loop over 64-byte chunks movdqa 5(%esi,%edx),%xmm1 movdqa 21(%esi,%edx),%xmm2 movdqa 37(%esi,%edx),%xmm3 movdqa 53(%esi,%edx),%xmm4 movdqa %xmm0,%xmm5 movdqa %xmm4,%xmm0 palignr $11,%xmm3,%xmm4 // dest <- shr( dest || source, imm*8 ) palignr $11,%xmm2,%xmm3 palignr $11,%xmm1,%xmm2 palignr $11,%xmm5,%xmm1 movdqa %xmm1,(%edi,%edx) movdqa %xmm2,16(%edi,%edx) movdqa %xmm3,32(%edi,%edx) movdqa %xmm4,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 1100 // We use the float single data type in order to use "movss" to merge vectors. LMod12: movss (%esi,%edx),%xmm0 // prefetch 1st four bytes of source, right justified jmp 1f .align 4,0x90 1: // loop over 64-byte chunks pshufd $(0x93),4(%esi,%edx),%xmm1 // load and rotate right 12 bytes (mask -- 10 01 00 11) pshufd $(0x93),20(%esi,%edx),%xmm2 pshufd $(0x93),36(%esi,%edx),%xmm3 pshufd $(0x93),52(%esi,%edx),%xmm4 movaps %xmm4,%xmm5 movss %xmm3,%xmm4 // copy low 4 bytes of source into destination movss %xmm2,%xmm3 movss %xmm1,%xmm2 movss %xmm0,%xmm1 movaps %xmm1,(%edi,%edx) movaps %xmm2,16(%edi,%edx) movaps %xmm5,%xmm0 movaps %xmm3,32(%edi,%edx) movaps %xmm4,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 1101 LMod13: movdqa -13(%esi,%edx),%xmm0 // prime the loop by loading 1st source dq 1: // loop over 64-byte chunks movdqa 3(%esi,%edx),%xmm1 movdqa 19(%esi,%edx),%xmm2 movdqa 35(%esi,%edx),%xmm3 movdqa 51(%esi,%edx),%xmm4 movdqa %xmm0,%xmm5 movdqa %xmm4,%xmm0 palignr $13,%xmm3,%xmm4 // dest <- shr( dest || source, imm*8 ) palignr $13,%xmm2,%xmm3 palignr $13,%xmm1,%xmm2 palignr $13,%xmm5,%xmm1 movdqa %xmm1,(%edi,%edx) movdqa %xmm2,16(%edi,%edx) movdqa %xmm3,32(%edi,%edx) movdqa %xmm4,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 1110 LMod14: movdqa -14(%esi,%edx),%xmm0 // prime the loop by loading 1st source dq 1: // loop over 64-byte chunks movdqa 2(%esi,%edx),%xmm1 movdqa 18(%esi,%edx),%xmm2 movdqa 34(%esi,%edx),%xmm3 movdqa 50(%esi,%edx),%xmm4 movdqa %xmm0,%xmm5 movdqa %xmm4,%xmm0 palignr $14,%xmm3,%xmm4 // dest <- shr( dest || source, imm*8 ) palignr $14,%xmm2,%xmm3 palignr $14,%xmm1,%xmm2 palignr $14,%xmm5,%xmm1 movdqa %xmm1,(%edi,%edx) movdqa %xmm2,16(%edi,%edx) movdqa %xmm3,32(%edi,%edx) movdqa %xmm4,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Forward loop for medium length operands in which low four bits of %esi == 1111 LMod15: movdqa -15(%esi,%edx),%xmm0 // prime the loop by loading 1st source dq 1: // loop over 64-byte chunks movdqa 1(%esi,%edx),%xmm1 movdqa 17(%esi,%edx),%xmm2 movdqa 33(%esi,%edx),%xmm3 movdqa 49(%esi,%edx),%xmm4 movdqa %xmm0,%xmm5 movdqa %xmm4,%xmm0 palignr $15,%xmm3,%xmm4 // dest <- shr( dest || source, imm*8 ) palignr $15,%xmm2,%xmm3 palignr $15,%xmm1,%xmm2 palignr $15,%xmm5,%xmm1 movdqa %xmm1,(%edi,%edx) movdqa %xmm2,16(%edi,%edx) movdqa %xmm3,32(%edi,%edx) movdqa %xmm4,48(%edi,%edx) addl $64,%edx jnz 1b jmp Lshort // copy remaining 0..63 bytes and done // Reverse moves. These are not optimized as aggressively as their forward // counterparts, as they are only used with destructive overlap. // ecx = length // esi = source ptr // edi = dest ptr LReverse: addl %ecx,%esi // point to end of strings addl %ecx,%edi cmpl $(kShort),%ecx // long enough to bother with SSE? ja LReverseNotShort // yes // Handle reverse short copies. // ecx = length // esi = one byte past end of source // edi = one byte past end of dest LReverseShort: movl %ecx,%edx // copy length shrl $2,%ecx // #words jz 3f 1: subl $4,%esi movl (%esi),%eax subl $4,%edi movl %eax,(%edi) dec %ecx jnz 1b 3: andl $3,%edx // bytes? jz 5f 4: dec %esi movb (%esi),%al dec %edi movb %al,(%edi) dec %edx jnz 4b 5: movl 8(%ebp),%eax // get return value (dst ptr) for memcpy/memmove popl %edi popl %esi popl %ebp ret // Handle a reverse move long enough to justify using SSE. // ecx = length // esi = one byte past end of source // edi = one byte past end of dest LReverseNotShort: movl %edi,%edx // copy destination andl $15,%edx // get #bytes to align destination je LReverseDestAligned // already aligned subl %edx,%ecx // adjust length 1: // loop copying 1..15 bytes dec %esi movb (%esi),%al dec %edi movb %al,(%edi) dec %edx jnz 1b // Destination is now aligned. Prepare for reverse loops. LReverseDestAligned: movl %ecx,%edx // copy length andl $63,%ecx // get remaining bytes for Lshort andl $-64,%edx // get number of bytes we will copy in inner loop subl %edx,%esi // point to endpoint of copy subl %edx,%edi testl $15,%esi // is source aligned too? jnz LReverseUnalignedLoop // no LReverseAlignedLoop: // loop over 64-byte chunks movdqa -16(%esi,%edx),%xmm0 movdqa -32(%esi,%edx),%xmm1 movdqa -48(%esi,%edx),%xmm2 movdqa -64(%esi,%edx),%xmm3 movdqa %xmm0,-16(%edi,%edx) movdqa %xmm1,-32(%edi,%edx) movdqa %xmm2,-48(%edi,%edx) movdqa %xmm3,-64(%edi,%edx) subl $64,%edx jne LReverseAlignedLoop jmp LReverseShort // copy remaining 0..63 bytes and done // Reverse, unaligned loop. LDDQU==MOVDQU on these machines. LReverseUnalignedLoop: // loop over 64-byte chunks movdqu -16(%esi,%edx),%xmm0 movdqu -32(%esi,%edx),%xmm1 movdqu -48(%esi,%edx),%xmm2 movdqu -64(%esi,%edx),%xmm3 movdqa %xmm0,-16(%edi,%edx) movdqa %xmm1,-32(%edi,%edx) movdqa %xmm2,-48(%edi,%edx) movdqa %xmm3,-64(%edi,%edx) subl $64,%edx jne LReverseUnalignedLoop jmp LReverseShort // copy remaining 0..63 bytes and done COMMPAGE_DESCRIPTOR(bcopy_sse3x,_COMM_PAGE_BCOPY,kHasSSE2+kHasSupplementalSSE3+kCache64,kHasSSE4_2)