| /* |
| * linux/arch/arm26/lib/csumpartial.S |
| * |
| * Copyright (C) 1995-1998 Russell King |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| */ |
| #include <linux/linkage.h> |
| #include <asm/assembler.h> |
| |
| .text |
| |
| /* |
| * Function: __u32 csum_partial(const char *src, int len, __u32 sum) |
| * Params : r0 = buffer, r1 = len, r2 = checksum |
| * Returns : r0 = new checksum |
| */ |
| |
| buf .req r0 |
| len .req r1 |
| sum .req r2 |
| td0 .req r3 |
| td1 .req r4 @ save before use |
| td2 .req r5 @ save before use |
| td3 .req lr |
| |
| .zero: mov r0, sum |
| add sp, sp, #4 |
| ldr pc, [sp], #4 |
| |
| /* |
| * Handle 0 to 7 bytes, with any alignment of source and |
| * destination pointers. Note that when we get here, C = 0 |
| */ |
| .less8: teq len, #0 @ check for zero count |
| beq .zero |
| |
| /* we must have at least one byte. */ |
| tst buf, #1 @ odd address? |
| ldrneb td0, [buf], #1 |
| subne len, len, #1 |
| adcnes sum, sum, td0, lsl #byte(1) |
| |
| .less4: tst len, #6 |
| beq .less8_byte |
| |
| /* we are now half-word aligned */ |
| |
| .less8_wordlp: |
| #if __LINUX_ARM_ARCH__ >= 4 |
| ldrh td0, [buf], #2 |
| sub len, len, #2 |
| #else |
| ldrb td0, [buf], #1 |
| ldrb td3, [buf], #1 |
| sub len, len, #2 |
| orr td0, td0, td3, lsl #8 |
| #endif |
| adcs sum, sum, td0 |
| tst len, #6 |
| bne .less8_wordlp |
| |
| .less8_byte: tst len, #1 @ odd number of bytes |
| ldrneb td0, [buf], #1 @ include last byte |
| adcnes sum, sum, td0, lsl #byte(0) @ update checksum |
| |
| .done: adc r0, sum, #0 @ collect up the last carry |
| ldr td0, [sp], #4 |
| tst td0, #1 @ check buffer alignment |
| movne td0, r0, lsl #8 @ rotate checksum by 8 bits |
| orrne r0, td0, r0, lsr #24 |
| ldr pc, [sp], #4 @ return |
| |
| .not_aligned: tst buf, #1 @ odd address |
| ldrneb td0, [buf], #1 @ make even |
| subne len, len, #1 |
| adcnes sum, sum, td0, lsl #byte(1) @ update checksum |
| |
| tst buf, #2 @ 32-bit aligned? |
| #if __LINUX_ARM_ARCH__ >= 4 |
| ldrneh td0, [buf], #2 @ make 32-bit aligned |
| subne len, len, #2 |
| #else |
| ldrneb td0, [buf], #1 |
| ldrneb ip, [buf], #1 |
| subne len, len, #2 |
| orrne td0, td0, ip, lsl #8 |
| #endif |
| adcnes sum, sum, td0 @ update checksum |
| mov pc, lr |
| |
| ENTRY(csum_partial) |
| stmfd sp!, {buf, lr} |
| cmp len, #8 @ Ensure that we have at least |
| blo .less8 @ 8 bytes to copy. |
| |
| adds sum, sum, #0 @ C = 0 |
| tst buf, #3 @ Test destination alignment |
| blne .not_aligned @ aligh destination, return here |
| |
| 1: bics ip, len, #31 |
| beq 3f |
| |
| stmfd sp!, {r4 - r5} |
| 2: ldmia buf!, {td0, td1, td2, td3} |
| adcs sum, sum, td0 |
| adcs sum, sum, td1 |
| adcs sum, sum, td2 |
| adcs sum, sum, td3 |
| ldmia buf!, {td0, td1, td2, td3} |
| adcs sum, sum, td0 |
| adcs sum, sum, td1 |
| adcs sum, sum, td2 |
| adcs sum, sum, td3 |
| sub ip, ip, #32 |
| teq ip, #0 |
| bne 2b |
| ldmfd sp!, {r4 - r5} |
| |
| 3: tst len, #0x1c @ should not change C |
| beq .less4 |
| |
| 4: ldr td0, [buf], #4 |
| sub len, len, #4 |
| adcs sum, sum, td0 |
| tst len, #0x1c |
| bne 4b |
| b .less4 |