diff options
Diffstat (limited to 'arch/cris/arch-v32/lib/checksumcopy.S')
| -rw-r--r-- | arch/cris/arch-v32/lib/checksumcopy.S | 69 |
1 files changed, 20 insertions, 49 deletions
diff --git a/arch/cris/arch-v32/lib/checksumcopy.S b/arch/cris/arch-v32/lib/checksumcopy.S index 9303ccbadc6d..21aabe91489b 100644 --- a/arch/cris/arch-v32/lib/checksumcopy.S +++ b/arch/cris/arch-v32/lib/checksumcopy.S @@ -1,6 +1,6 @@ /* * A fast checksum+copy routine using movem - * Copyright (c) 1998, 2001, 2003 Axis Communications AB + * Copyright (c) 1998-2007 Axis Communications AB * * Authors: Bjorn Wesen * @@ -16,32 +16,23 @@ csum_partial_copy_nocheck: ;; r12 - length ;; r13 - checksum - ;; check for breakeven length between movem and normal word looping versions - ;; we also do _NOT_ want to compute a checksum over more than the - ;; actual length when length < 40 - - cmpu.w 80,$r12 - blo _word_loop - nop - - ;; need to save the registers we use below in the movem loop - ;; this overhead is why we have a check above for breakeven length - ;; only r0 - r8 have to be saved, the other ones are clobber-able - ;; according to the ABI + ;; Optimized for large packets + subq 10*4, $r12 + blt _word_loop + move.d $r12, $acr subq 9*4,$sp - subq 10*4,$r12 ; update length for the first loop + clearf c movem $r8,[$sp] ;; do a movem copy and checksum - 1: ;; A failing userspace access (the read) will have this as PC. _mloop: movem [$r10+],$r9 ; read 10 longwords + addoq -10*4, $acr, $acr ; loop counter in latency cycle movem $r9,[$r11+] ; write 10 longwords ;; perform dword checksumming on the 10 longwords - - add.d $r0,$r13 + addc $r0,$r13 addc $r1,$r13 addc $r2,$r13 addc $r3,$r13 @@ -52,47 +43,30 @@ _mloop: movem [$r10+],$r9 ; read 10 longwords addc $r8,$r13 addc $r9,$r13 - ;; fold the carry into the checksum, to avoid having to loop the carry - ;; back into the top - - addc 0,$r13 - addc 0,$r13 ; do it again, since we might have generated a carry - - subq 10*4,$r12 - bge _mloop - nop - - addq 10*4,$r12 ; compensate for last loop underflowing length + ;; test $acr, without trashing carry. + move.d $acr, $acr + bpl _mloop + ;; r12 <= acr is needed after mloop and in the exception handlers. + move.d $acr, $r12 + ;; fold the last carry into r13 + addc 0, $r13 movem [$sp+],$r8 ; restore regs _word_loop: - ;; only fold if there is anything to fold. - - cmpq 0,$r13 - beq _no_fold + addq 10*4,$r12 ; compensate for last loop underflowing length ;; fold 32-bit checksum into a 16-bit checksum, to avoid carries below ;; r9 can be used as temporary. - move.d $r13,$r9 lsrq 16,$r9 ; r0 = checksum >> 16 and.d 0xffff,$r13 ; checksum = checksum & 0xffff - add.d $r9,$r13 ; checksum += r0 - move.d $r13,$r9 ; do the same again, maybe we got a carry last add - lsrq 16,$r9 - and.d 0xffff,$r13 - add.d $r9,$r13 -_no_fold: - cmpq 2,$r12 + subq 2, $r12 blt _no_words - nop + add.d $r9,$r13 ; checksum += r0 ;; copy and checksum the rest of the words - - subq 2,$r12 - 2: ;; A failing userspace access for the read below will have this as PC. _wloop: move.w [$r10+],$r9 addu.w $r9,$r13 @@ -100,12 +74,9 @@ _wloop: move.w [$r10+],$r9 bge _wloop move.w $r9,[$r11+] - addq 2,$r12 - _no_words: - ;; see if we have one odd byte more - cmpq 1,$r12 - beq _do_byte + addq 2,$r12 + bne _do_byte nop ret move.d $r13,$r10 |