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[/] [or1k/] [trunk/] [linux/] [linux-2.4/] [arch/] [arm/] [lib/] [csumpartial.S] - Blame information for rev 1275

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1 1275 phoenix
/*
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 *  linux/arch/arm/lib/csumpartial.S
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 *
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 *  Copyright (C) 1995-1998 Russell King
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 *
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 * This program is free software; you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License version 2 as
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 * published by the Free Software Foundation.
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 */
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#include 
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#include 
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                .text
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/*
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 * Function: __u32 csum_partial(const char *src, int len, __u32 sum)
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 * Params  : r0 = buffer, r1 = len, r2 = checksum
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 * Returns : r0 = new checksum
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 */
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buf     .req    r0
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len     .req    r1
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sum     .req    r2
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td0     .req    r3
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td1     .req    r4      @ save before use
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td2     .req    r5      @ save before use
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td3     .req    lr
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.zero:          mov     r0, sum
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                add     sp, sp, #4
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                ldr     pc, [sp], #4
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                /*
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                 * Handle 0 to 7 bytes, with any alignment of source and
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                 * destination pointers.  Note that when we get here, C = 0
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                 */
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.less8:         teq     len, #0                 @ check for zero count
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                beq     .zero
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                /* we must have at least one byte. */
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                tst     buf, #1                 @ odd address?
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                ldrneb  td0, [buf], #1
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                subne   len, len, #1
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                adcnes  sum, sum, td0, lsl #8
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.less4:         tst     len, #6
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                beq     .less8_byte
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                /* we are now half-word aligned */
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.less8_wordlp:
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#if __LINUX_ARM_ARCH__ >= 4
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                ldrh    td0, [buf]
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                add     buf, buf, #2
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                sub     len, len, #2
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#else
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                ldrb    td0, [buf], #1
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                ldrb    td3, [buf], #1
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                sub     len, len, #2
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                orr     td0, td0, td3, lsl #8
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#endif
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                adcs    sum, sum, td0
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                tst     len, #6
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                bne     .less8_wordlp
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.less8_byte:    tst     len, #1                 @ odd number of bytes
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                ldrneb  td0, [buf], #1          @ include last byte
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                adcnes  sum, sum, td0           @ update checksum
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.done:          adc     r0, sum, #0             @ collect up the last carry
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                ldr     td0, [sp], #4
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                tst     td0, #1                 @ check buffer alignment
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                movne   td0, r0, lsl #8         @ rotate checksum by 8 bits
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                orrne   r0, td0, r0, lsr #24
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                ldr     pc, [sp], #4            @ return
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.not_aligned:   tst     buf, #1                 @ odd address
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                ldrneb  td0, [buf], #1          @ make even
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                subne   len, len, #1
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                adcnes  sum, sum, td0, lsl #8   @ update checksum
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                tst     buf, #2                 @ 32-bit aligned?
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#if __LINUX_ARM_ARCH__ >= 4
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                ldrneh  td0, [buf]              @ make 32-bit aligned
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                add     buf, buf, #2
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                subne   len, len, #2
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#else
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                ldrneb  td0, [buf], #1
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                ldrneb  ip, [buf], #1
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                subne   len, len, #2
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                orrne   td0, td0, ip, lsl #8
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#endif
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                adcnes  sum, sum, td0           @ update checksum
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                mov     pc, lr
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ENTRY(csum_partial)
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                stmfd   sp!, {buf, lr}
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                cmp     len, #8                 @ Ensure that we have at least
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                blo     .less8                  @ 8 bytes to copy.
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                adds    sum, sum, #0            @ C = 0
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                tst     buf, #3                 @ Test destination alignment
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                blne    .not_aligned            @ aligh destination, return here
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1:              bics    ip, len, #31
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                beq     3f
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                stmfd   sp!, {r4 - r5}
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2:              ldmia   buf!, {td0, td1, td2, td3}
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                adcs    sum, sum, td0
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                adcs    sum, sum, td1
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                adcs    sum, sum, td2
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                adcs    sum, sum, td3
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                ldmia   buf!, {td0, td1, td2, td3}
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                adcs    sum, sum, td0
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                adcs    sum, sum, td1
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                adcs    sum, sum, td2
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                adcs    sum, sum, td3
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                sub     ip, ip, #32
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                teq     ip, #0
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                bne     2b
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                ldmfd   sp!, {r4 - r5}
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3:              tst     len, #0x1c              @ should not change C
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                beq     .less4
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4:              ldr     td0, [buf], #4
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                sub     len, len, #4
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                adcs    sum, sum, td0
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                tst     len, #0x1c
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                bne     4b
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                b       .less4

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