// SPDX-License-Identifier: GPL-2.0+ /* * Copyright (C) 1991,1992,1993,1997,1998,2003, 2005 Free Software Foundation, Inc. * This file is part of the GNU C Library. * Copyright (c) 2011 The Chromium OS Authors. */ /* From glibc-2.14, sysdeps/i386/memset.c */ #include #include #include typedef uint32_t op_t; void *memset(void *dstpp, int c, size_t len) { int d0; unsigned long int dstp = (unsigned long int) dstpp; /* This explicit register allocation improves code very much indeed. */ register op_t x asm("ax"); x = (unsigned char) c; /* Clear the direction flag, so filling will move forward. */ asm volatile("cld"); /* This threshold value is optimal. */ if (len >= 12) { /* Fill X with four copies of the char we want to fill with. */ x |= (x << 8); x |= (x << 16); /* Adjust LEN for the bytes handled in the first loop. */ len -= (-dstp) % sizeof(op_t); /* * There are at least some bytes to set. No need to test for * LEN == 0 in this alignment loop. */ /* Fill bytes until DSTP is aligned on a longword boundary. */ asm volatile( "rep\n" "stosb" /* %0, %2, %3 */ : "=D" (dstp), "=c" (d0) : "0" (dstp), "1" ((-dstp) % sizeof(op_t)), "a" (x) : "memory"); /* Fill longwords. */ asm volatile( "rep\n" "stosl" /* %0, %2, %3 */ : "=D" (dstp), "=c" (d0) : "0" (dstp), "1" (len / sizeof(op_t)), "a" (x) : "memory"); len %= sizeof(op_t); } /* Write the last few bytes. */ asm volatile( "rep\n" "stosb" /* %0, %2, %3 */ : "=D" (dstp), "=c" (d0) : "0" (dstp), "1" (len), "a" (x) : "memory"); return dstpp; } #define OP_T_THRES 8 #define OPSIZ (sizeof(op_t)) #define BYTE_COPY_FWD(dst_bp, src_bp, nbytes) \ do { \ int __d0; \ asm volatile( \ /* Clear the direction flag, so copying goes forward. */ \ "cld\n" \ /* Copy bytes. */ \ "rep\n" \ "movsb" : \ "=D" (dst_bp), "=S" (src_bp), "=c" (__d0) : \ "0" (dst_bp), "1" (src_bp), "2" (nbytes) : \ "memory"); \ } while (0) #define WORD_COPY_FWD(dst_bp, src_bp, nbytes_left, nbytes) \ do { \ int __d0; \ asm volatile( \ /* Clear the direction flag, so copying goes forward. */ \ "cld\n" \ /* Copy longwords. */ \ "rep\n" \ "movsl" : \ "=D" (dst_bp), "=S" (src_bp), "=c" (__d0) : \ "0" (dst_bp), "1" (src_bp), "2" ((nbytes) / 4) : \ "memory"); \ (nbytes_left) = (nbytes) % 4; \ } while (0) void *memcpy(void *dstpp, const void *srcpp, size_t len) { unsigned long int dstp = (long int)dstpp; unsigned long int srcp = (long int)srcpp; /* Copy from the beginning to the end. */ /* If there not too few bytes to copy, use word copy. */ if (len >= OP_T_THRES) { /* Copy just a few bytes to make DSTP aligned. */ len -= (-dstp) % OPSIZ; BYTE_COPY_FWD(dstp, srcp, (-dstp) % OPSIZ); /* Copy from SRCP to DSTP taking advantage of the known * alignment of DSTP. Number of bytes remaining is put * in the third argument, i.e. in LEN. This number may * vary from machine to machine. */ WORD_COPY_FWD(dstp, srcp, len, len); /* Fall out and copy the tail. */ } /* There are just a few bytes to copy. Use byte memory operations. */ BYTE_COPY_FWD(dstp, srcp, len); return dstpp; } void *memmove(void *dest, const void *src, size_t n) { int d0, d1, d2, d3, d4, d5; char *ret = dest; __asm__ __volatile__( /* Handle more 16 bytes in loop */ "cmp $0x10, %0\n\t" "jb 1f\n\t" /* Decide forward/backward copy mode */ "cmp %2, %1\n\t" "jb 2f\n\t" /* * movs instruction have many startup latency * so we handle small size by general register. */ "cmp $680, %0\n\t" "jb 3f\n\t" /* movs instruction is only good for aligned case */ "mov %1, %3\n\t" "xor %2, %3\n\t" "and $0xff, %3\n\t" "jz 4f\n\t" "3:\n\t" "sub $0x10, %0\n\t" /* We gobble 16 bytes forward in each loop */ "3:\n\t" "sub $0x10, %0\n\t" "mov 0*4(%1), %3\n\t" "mov 1*4(%1), %4\n\t" "mov %3, 0*4(%2)\n\t" "mov %4, 1*4(%2)\n\t" "mov 2*4(%1), %3\n\t" "mov 3*4(%1), %4\n\t" "mov %3, 2*4(%2)\n\t" "mov %4, 3*4(%2)\n\t" "lea 0x10(%1), %1\n\t" "lea 0x10(%2), %2\n\t" "jae 3b\n\t" "add $0x10, %0\n\t" "jmp 1f\n\t" /* Handle data forward by movs */ ".p2align 4\n\t" "4:\n\t" "mov -4(%1, %0), %3\n\t" "lea -4(%2, %0), %4\n\t" "shr $2, %0\n\t" "rep movsl\n\t" "mov %3, (%4)\n\t" "jmp 11f\n\t" /* Handle data backward by movs */ ".p2align 4\n\t" "6:\n\t" "mov (%1), %3\n\t" "mov %2, %4\n\t" "lea -4(%1, %0), %1\n\t" "lea -4(%2, %0), %2\n\t" "shr $2, %0\n\t" "std\n\t" "rep movsl\n\t" "mov %3,(%4)\n\t" "cld\n\t" "jmp 11f\n\t" /* Start to prepare for backward copy */ ".p2align 4\n\t" "2:\n\t" "cmp $680, %0\n\t" "jb 5f\n\t" "mov %1, %3\n\t" "xor %2, %3\n\t" "and $0xff, %3\n\t" "jz 6b\n\t" /* Calculate copy position to tail */ "5:\n\t" "add %0, %1\n\t" "add %0, %2\n\t" "sub $0x10, %0\n\t" /* We gobble 16 bytes backward in each loop */ "7:\n\t" "sub $0x10, %0\n\t" "mov -1*4(%1), %3\n\t" "mov -2*4(%1), %4\n\t" "mov %3, -1*4(%2)\n\t" "mov %4, -2*4(%2)\n\t" "mov -3*4(%1), %3\n\t" "mov -4*4(%1), %4\n\t" "mov %3, -3*4(%2)\n\t" "mov %4, -4*4(%2)\n\t" "lea -0x10(%1), %1\n\t" "lea -0x10(%2), %2\n\t" "jae 7b\n\t" /* Calculate copy position to head */ "add $0x10, %0\n\t" "sub %0, %1\n\t" "sub %0, %2\n\t" /* Move data from 8 bytes to 15 bytes */ ".p2align 4\n\t" "1:\n\t" "cmp $8, %0\n\t" "jb 8f\n\t" "mov 0*4(%1), %3\n\t" "mov 1*4(%1), %4\n\t" "mov -2*4(%1, %0), %5\n\t" "mov -1*4(%1, %0), %1\n\t" "mov %3, 0*4(%2)\n\t" "mov %4, 1*4(%2)\n\t" "mov %5, -2*4(%2, %0)\n\t" "mov %1, -1*4(%2, %0)\n\t" "jmp 11f\n\t" /* Move data from 4 bytes to 7 bytes */ ".p2align 4\n\t" "8:\n\t" "cmp $4, %0\n\t" "jb 9f\n\t" "mov 0*4(%1), %3\n\t" "mov -1*4(%1, %0), %4\n\t" "mov %3, 0*4(%2)\n\t" "mov %4, -1*4(%2, %0)\n\t" "jmp 11f\n\t" /* Move data from 2 bytes to 3 bytes */ ".p2align 4\n\t" "9:\n\t" "cmp $2, %0\n\t" "jb 10f\n\t" "movw 0*2(%1), %%dx\n\t" "movw -1*2(%1, %0), %%bx\n\t" "movw %%dx, 0*2(%2)\n\t" "movw %%bx, -1*2(%2, %0)\n\t" "jmp 11f\n\t" /* Move data for 1 byte */ ".p2align 4\n\t" "10:\n\t" "cmp $1, %0\n\t" "jb 11f\n\t" "movb (%1), %%cl\n\t" "movb %%cl, (%2)\n\t" ".p2align 4\n\t" "11:" : "=&c" (d0), "=&S" (d1), "=&D" (d2), "=r" (d3), "=r" (d4), "=r"(d5) : "0" (n), "1" (src), "2" (dest) : "memory"); return ret; }