| /* |
| * Optmized version of the ip_fast_csum() function |
| * Used for calculating IP header checksum |
| * |
| * Return: 16bit checksum, complemented |
| * |
| * Inputs: |
| * in0: address of buffer to checksum (char *) |
| * in1: length of the buffer (int) |
| * |
| * Copyright (C) 2002 Intel Corp. |
| * Copyright (C) 2002 Ken Chen <kenneth.w.chen@intel.com> |
| */ |
| |
| #include <asm/asmmacro.h> |
| |
| /* |
| * Since we know that most likely this function is called with buf aligned |
| * on 4-byte boundary and 20 bytes in length, we can execution rather quickly |
| * versus calling generic version of do_csum, which has lots of overhead in |
| * handling various alignments and sizes. However, due to lack of constrains |
| * put on the function input argument, cases with alignment not on 4-byte or |
| * size not equal to 20 bytes will be handled by the generic do_csum function. |
| */ |
| |
| #define in0 r32 |
| #define in1 r33 |
| #define ret0 r8 |
| |
| GLOBAL_ENTRY(ip_fast_csum) |
| .prologue |
| .body |
| cmp.ne p6,p7=5,in1 // size other than 20 byte? |
| and r14=3,in0 // is it aligned on 4-byte? |
| add r15=4,in0 // second source pointer |
| ;; |
| cmp.ne.or.andcm p6,p7=r14,r0 |
| ;; |
| (p7) ld4 r20=[in0],8 |
| (p7) ld4 r21=[r15],8 |
| (p6) br.spnt .generic |
| ;; |
| ld4 r22=[in0],8 |
| ld4 r23=[r15],8 |
| ;; |
| ld4 r24=[in0] |
| add r20=r20,r21 |
| add r22=r22,r23 |
| ;; |
| add r20=r20,r22 |
| ;; |
| add r20=r20,r24 |
| ;; |
| shr.u ret0=r20,16 // now need to add the carry |
| zxt2 r20=r20 |
| ;; |
| add r20=ret0,r20 |
| ;; |
| shr.u ret0=r20,16 // add carry again |
| zxt2 r20=r20 |
| ;; |
| add r20=ret0,r20 |
| ;; |
| shr.u ret0=r20,16 |
| zxt2 r20=r20 |
| ;; |
| add r20=ret0,r20 |
| ;; |
| andcm ret0=-1,r20 |
| .restore sp // reset frame state |
| br.ret.sptk.many b0 |
| ;; |
| |
| .generic: |
| .prologue |
| .save ar.pfs, r35 |
| alloc r35=ar.pfs,2,2,2,0 |
| .save rp, r34 |
| mov r34=b0 |
| .body |
| dep.z out1=in1,2,30 |
| mov out0=in0 |
| ;; |
| br.call.sptk.many b0=do_csum |
| ;; |
| andcm ret0=-1,ret0 |
| mov ar.pfs=r35 |
| mov b0=r34 |
| br.ret.sptk.many b0 |
| END(ip_fast_csum) |
