/* * Copyright (c) 2014 Travis Geiselbrecht * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files * (the "Software"), to deal in the Software without restriction, * including without limitation the rights to use, copy, modify, merge, * publish, distribute, sublicense, and/or sell copies of the Software, * and to permit persons to whom the Software is furnished to do so, * subject to the following conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #include #include .text .syntax unified .thumb .align 2 /* void bcopy(const void *src, void *dest, size_t n); */ FUNCTION(bcopy) // swap args for bcopy mov r12, r0 mov r0, r1 mov r1, r12 /* void *memcpy(void *dest, const void *src, size_t count) */ FUNCTION(memcpy) push { r0, r14 } // test for zero length or pointers being equivalent cbz r2, .L_done cmp r0, r1 beq .L_done // check for a short copy len cmp r2, #16 blt .L_bytewise // check to see if the pointers are similarly dword aligned eors r3, r0, r1 ands r3, #7 beq .L_prepare_dword // see how many bytes we need to move to align dest to word boundary and r3, r0, #3 cbz r3, .L_prepare_wordwise rsb r3, #4 subs r2, r3 .align 2 .L_bytewise_align: // bytewise to align memcpy ldrb r12, [r1], #1 subs r3, r3, #1 strb r12, [r0], #1 bgt .L_bytewise_align .L_prepare_wordwise: // load the number of words left lsrs r3, r2, #2 .align 2 .L_wordwise: // wordwise copy ldr r12, [r1], #4 subs r3, r3, #1 str r12, [r0], #4 bgt .L_wordwise // remaining bytes ands r2, #3 beq .L_done .align 2 .L_bytewise: // simple bytewise copy ldrb r12, [r1], #1 subs r2, r2, #1 strb r12, [r0], #1 bgt .L_bytewise .L_done: pop { r0, pc } // Handle copying by dword (8 bytes at a time) increments .L_prepare_dword: // see how many bytes we need to move to align dest to dword boundary and r3, r0, #7 cbz r3, .L_prepare_dwordwise rsb r3, #8 subs r2, r3 .align 2 .L_bytewise_align_dword: // bytewise to align memcpy ldrb r12, [r1], #1 subs r3, r3, #1 strb r12, [r0], #1 bgt .L_bytewise_align_dword .L_prepare_dwordwise: // load the number of dwords left lsrs r3, r2, #3 push { r5 } .align 2 .L_dwordwise: // dwordwise copy ldrd r5, r12, [r1], #8 subs r3, r3, #1 strd r5, r12, [r0], #8 bgt .L_dwordwise pop { r5 } // remaining bytes ands r2, #7 beq .L_done // finish the remaining bytes and exit b .L_bytewise