Diff: EthernetInterface/lwip-sys/arch/checksum.c

Revision:

9:58eb378727d9

Parent:

8:80d49dd91542

Child:

10:0b5e0dfee08e

diff -r 80d49dd91542 -r 58eb378727d9 EthernetInterface/lwip-sys/arch/checksum.c
--- a/EthernetInterface/lwip-sys/arch/checksum.c	Wed Oct 01 13:27:35 2014 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,126 +0,0 @@
-/* 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__)
-
-
-/* This is a hand written Thumb-2 assembly language version of the
-   algorithm 3 version of lwip_standard_chksum in lwIP's inet_chksum.c.  It
-   performs the checksumming 32-bits at a time and even unrolls the loop to
-   perform two of these 32-bit adds per loop iteration.
-   
-   Returns:
-        16-bit 1's complement summation (not inversed).
-        
-   NOTE: This function does return a uint16_t from the assembly language code
-         but is marked as void so that GCC doesn't issue warning because it
-         doesn't know about this low level return.
-*/
-__attribute__((naked)) void /*uint16_t*/ thumb2_checksum(const void* pData, int length)
-{
-    __asm (
-        ".syntax unified\n"
-        ".thumb\n"
-
-        // Push non-volatile registers we use on stack.  Push link register too to
-        // keep stack 8-byte aligned and allow single pop to restore and return.
-        "    push        {r4, lr}\n"
-        // Initialize sum, r2, to 0.
-        "    movs    r2, #0\n"
-        // Remember whether pData was at odd address in r3.  This is used later to
-        // know if it needs to swap the result since the summation will be done at
-        // an offset of 1, rather than 0.
-        "    ands    r3, r0, #1\n"
-        // Need to 2-byte align?  If not skip ahead.
-        "    beq     1$\n"
-        // We can return if there are no bytes to sum.
-        "    cbz     r1, 9$\n"
-
-        // 2-byte align.
-        // Place the first data byte in odd summation location since it needs to be
-        // swapped later.  It's ok to overwrite r2 here as it only had a value of 0
-        // up until now.  Advance r0 pointer and decrement r1 length as we go.
-        "    ldrb    r2, [r0], #1\n"
-        "    lsls    r2, r2, #8\n"
-        "    subs    r1, r1, #1\n"
-
-        // Need to 4-byte align?  If not skip ahead.
-        "1$:\n"
-        "    ands    r4, r0, #3\n"
-        "    beq     2$\n"
-        // Have more than 1 byte left to align?  If not skip ahead to take care of
-        // trailing byte.
-        "    cmp     r1, #2\n"
-        "    blt     7$\n"
-
-        // 4-byte align.
-        "    ldrh    r4, [r0], #2\n"
-        "    adds    r2, r2, r4\n"
-        "    subs    r1, r1, #2\n"
-
-        // Main summing loop which sums up data 2 words at a time.
-        // Make sure that we have more than 7 bytes left to sum.
-        "2$:\n"
-        "    cmp     r1, #8\n"
-        "    blt     3$\n"
-        // Sum next two words.  Applying previous upper 16-bit carry to
-        // lower 16-bits.
-        "    ldr     r4, [r0], #4\n"
-        "    adds    r2, r4\n"
-        "    adc     r2, r2, #0\n"
-        "    ldr     r4, [r0], #4\n"
-        "    adds    r2, r4\n"
-        "    adc     r2, r2, #0\n"
-        "    subs    r1, r1, #8\n"
-        "    b       2$\n"
-
-        // Sum up any remaining half-words.
-        "3$:\n"
-        // Make sure that we have more than 1 byte left to sum.
-        "    cmp     r1, #2\n"
-        "    blt     7$\n"
-        // Sum up next half word, continue to apply carry.
-        "    ldrh    r4, [r0], #2\n"
-        "    adds    r2, r4\n"
-        "    adc     r2, r2, #0\n"
-        "    subs    r1, r1, #2\n"
-        "    b       3$\n"
-
-        // Handle trailing byte, if it exists
-        "7$:\n"
-        "    cbz     r1, 8$\n"
-        "    ldrb    r4, [r0]\n"
-        "    adds    r2, r4\n"
-        "    adc     r2, r2, #0\n"
-
-        // Fold 32-bit checksum into 16-bit checksum.
-        "8$:\n"
-        "    ubfx    r4, r2, #16, #16\n"
-        "    ubfx    r2, r2, #0, #16\n"
-        "    adds    r2, r4\n"
-        "    ubfx    r4, r2, #16, #16\n"
-        "    ubfx    r2, r2, #0, #16\n"
-        "    adds    r2, r4\n"
-
-        // Swap bytes if started at odd address
-        "    cbz     r3, 9$\n"
-        "    rev16   r2, r2\n"
-
-        // Return final sum.
-        "9$: mov     r0, r2\n"
-        "    pop     {r4, pc}\n"
-    );
-}
-
-#endif