1 files changed, 120 insertions, 0 deletions

diff --git a/arch/cris/arch-v32/lib/checksumcopy.S b/arch/cris/arch-v32/lib/checksumcopy.S
new file mode 100644
index 000000000000..9303ccbadc6d
--- /dev/null
+++ b/arch/cris/arch-v32/lib/checksumcopy.S
@@ -0,0 +1,120 @@
+/*
+ * A fast checksum+copy routine using movem
+ * Copyright (c) 1998, 2001, 2003 Axis Communications AB
+ *
+ * Authors:     Bjorn Wesen
+ *
+ * csum_partial_copy_nocheck(const char *src, char *dst,
+ *                           int len, unsigned int sum)
+ */
+
+        .globl  csum_partial_copy_nocheck
+csum_partial_copy_nocheck:
+
+        ;; r10 - src
+        ;; r11 - dst
+        ;; 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,$r12
+        blo     _word_loop
+        nop
+
+        ;; need to save the registers we use below in the movem loop
+        ;; this overhead is why we have a check above for breakeven length
+        ;; only r0 - r8 have to be saved, the other ones are clobber-able
+        ;; according to the ABI
+
+        subq    9*4,$sp
+        subq    10*4,$r12       ; update length for the first loop
+        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
+        movem   $r9,[$r11+]     ; write 10 longwords
+
+        ;; perform dword checksumming on the 10 longwords
+
+        add.d   $r0,$r13
+        addc    $r1,$r13
+        addc    $r2,$r13
+        addc    $r3,$r13
+        addc    $r4,$r13
+        addc    $r5,$r13
+        addc    $r6,$r13
+        addc    $r7,$r13
+        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
+
+        movem   [$sp+],$r8      ; restore regs
+
+_word_loop:
+        ;; only fold if there is anything to fold.
+
+        cmpq    0,$r13
+        beq     _no_fold
+
+        ;; 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,$r12
+        blt     _no_words
+        nop
+
+        ;; copy and checksum the rest of the words
+
+        subq    2,$r12
+
+2:      ;; A failing userspace access for the read below will have this as PC.
+_wloop: move.w  [$r10+],$r9
+        addu.w  $r9,$r13
+        subq    2,$r12
+        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
+        nop
+        ret
+        move.d  $r13,$r10
+
+_do_byte:
+        ;; copy and checksum the last byte
+3:      ;; A failing userspace access for the read below will have this as PC.
+        move.b  [$r10],$r9
+        addu.b  $r9,$r13
+        move.b  $r9,[$r11]
+        ret
+        move.d  $r13,$r10