LXR linux/arch/metag/lib/ip_fast

   1
   2        .text
   3/*
   4 * This is a version of ip_compute_csum() optimized for IP headers,
   5 * which always checksum on 4 octet boundaries.
   6 *
   7 * extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
   8 *
   9 */
  10        .global _ip_fast_csum
  11        .type   _ip_fast_csum,function
  12_ip_fast_csum:
  13        !! TXRPT needs loops - 1
  14        SUBS    TXRPT,D0Ar2,#1
  15        MOV     D0Re0,#0
  16        BLO     $Lfast_csum_exit
  17$Lfast_csum_loop:
  18        GETD    D1Ar3,[D1Ar1++]
  19        ADDS    D0Re0,D0Re0,D1Ar3
  20        ADDCS   D0Re0,D0Re0,#1
  21        BR      $Lfast_csum_loop
  22        LSR     D0Ar4,D0Re0,#16
  23        AND     D0Re0,D0Re0,#0xffff
  24        AND     D0Ar4,D0Ar4,#0xffff
  25        ADD     D0Re0,D0Re0,D0Ar4
  26        LSR     D0Ar4,D0Re0,#16
  27        ADD     D0Re0,D0Re0,D0Ar4
  28        XOR     D0Re0,D0Re0,#-1
  29        AND     D0Re0,D0Re0,#0xffff
  30$Lfast_csum_exit:
  31        MOV     PC,D1RtP
  32        .size _ip_fast_csum,.-_ip_fast_csum
  33