diff options
Diffstat (limited to 'tool/mbed/mbed-sdk/libraries/net/lwip/lwip-sys/arch/memcpy.c')
-rw-r--r-- | tool/mbed/mbed-sdk/libraries/net/lwip/lwip-sys/arch/memcpy.c | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/tool/mbed/mbed-sdk/libraries/net/lwip/lwip-sys/arch/memcpy.c b/tool/mbed/mbed-sdk/libraries/net/lwip/lwip-sys/arch/memcpy.c new file mode 100644 index 0000000000..fefbcda3c2 --- /dev/null +++ b/tool/mbed/mbed-sdk/libraries/net/lwip/lwip-sys/arch/memcpy.c @@ -0,0 +1,59 @@ +/* Copyright (C) 2013 - Adam Green (https://github.com/adamgreen) + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. +*/ +#if defined(TOOLCHAIN_GCC) && defined(__thumb2__) + +#include <stdio.h> + + +/* This is a hand written Thumb-2 assembly language version of the + standard C memcpy() function that can be used by the lwIP networking + stack to improve its performance. It copies 4 bytes at a time and + unrolls the loop to perform 4 of these copies per loop iteration. +*/ +__attribute__((naked)) void thumb2_memcpy(void* pDest, const void* pSource, size_t length) +{ + __asm ( + ".syntax unified\n" + ".thumb\n" + + // Copy 16 bytes at a time first. + " lsrs r3, r2, #4\n" + " beq.n 2$\n" + "1$: ldr r12, [r1], #4\n" + " str r12, [r0], #4\n" + " ldr r12, [r1], #4\n" + " str r12, [r0], #4\n" + " ldr r12, [r1], #4\n" + " str r12, [r0], #4\n" + " ldr r12, [r1], #4\n" + " str r12, [r0], #4\n" + " subs r3, #1\n" + " bne 1$\n" + + // Copy byte by byte for what is left. + "2$:\n" + " ands r3, r2, #0xf\n" + " beq.n 4$\n" + "3$: ldrb r12, [r1], #1\n" + " strb r12, [r0], #1\n" + " subs r3, #1\n" + " bne 3$\n" + + // Return to caller. + "4$: bx lr\n" + ); +} + +#endif |