1/* 2 * Optmized version of the ip_fast_csum() function 3 * Used for calculating IP header checksum 4 * 5 * Return: 16bit checksum, complemented 6 * 7 * Inputs: 8 * in0: address of buffer to checksum (char *) 9 * in1: length of the buffer (int) 10 * 11 * Copyright (C) 2002, 2006 Intel Corp. 12 * Copyright (C) 2002, 2006 Ken Chen <kenneth.w.chen@intel.com> 13 */ 14 15#include <asm/asmmacro.h> 16 17/* 18 * Since we know that most likely this function is called with buf aligned 19 * on 4-byte boundary and 20 bytes in length, we can execution rather quickly 20 * versus calling generic version of do_csum, which has lots of overhead in 21 * handling various alignments and sizes. However, due to lack of constrains 22 * put on the function input argument, cases with alignment not on 4-byte or 23 * size not equal to 20 bytes will be handled by the generic do_csum function. 24 */ 25 26#define in0 r32 27#define in1 r33 28#define in2 r34 29#define in3 r35 30#define in4 r36 31#define ret0 r8 32 33GLOBAL_ENTRY(ip_fast_csum) 34 .prologue 35 .body 36 cmp.ne p6,p7=5,in1 // size other than 20 byte? 37 and r14=3,in0 // is it aligned on 4-byte? 38 add r15=4,in0 // second source pointer 39 ;; 40 cmp.ne.or.andcm p6,p7=r14,r0 41 ;; 42(p7) ld4 r20=[in0],8 43(p7) ld4 r21=[r15],8 44(p6) br.spnt .generic 45 ;; 46 ld4 r22=[in0],8 47 ld4 r23=[r15],8 48 ;; 49 ld4 r24=[in0] 50 add r20=r20,r21 51 add r22=r22,r23 52 ;; 53 add r20=r20,r22 54 ;; 55 add r20=r20,r24 56 ;; 57 shr.u ret0=r20,16 // now need to add the carry 58 zxt2 r20=r20 59 ;; 60 add r20=ret0,r20 61 ;; 62 shr.u ret0=r20,16 // add carry again 63 zxt2 r20=r20 64 ;; 65 add r20=ret0,r20 66 ;; 67 shr.u ret0=r20,16 68 zxt2 r20=r20 69 ;; 70 add r20=ret0,r20 71 mov r9=0xffff 72 ;; 73 andcm ret0=r9,r20 74 .restore sp // reset frame state 75 br.ret.sptk.many b0 76 ;; 77 78.generic: 79 .prologue 80 .save ar.pfs, r35 81 alloc r35=ar.pfs,2,2,2,0 82 .save rp, r34 83 mov r34=b0 84 .body 85 dep.z out1=in1,2,30 86 mov out0=in0 87 ;; 88 br.call.sptk.many b0=do_csum 89 ;; 90 andcm ret0=-1,ret0 91 mov ar.pfs=r35 92 mov b0=r34 93 br.ret.sptk.many b0 94END(ip_fast_csum) 95 96GLOBAL_ENTRY(csum_ipv6_magic) 97 ld4 r20=[in0],4 98 ld4 r21=[in1],4 99 zxt4 in2=in2 100 ;; 101 ld4 r22=[in0],4 102 ld4 r23=[in1],4 103 dep r15=in3,in2,32,16 104 ;; 105 ld4 r24=[in0],4 106 ld4 r25=[in1],4 107 mux1 r15=r15,@rev 108 add r16=r20,r21 109 add r17=r22,r23 110 zxt4 in4=in4 111 ;; 112 ld4 r26=[in0],4 113 ld4 r27=[in1],4 114 shr.u r15=r15,16 115 add r18=r24,r25 116 add r8=r16,r17 117 ;; 118 add r19=r26,r27 119 add r8=r8,r18 120 ;; 121 add r8=r8,r19 122 add r15=r15,in4 123 ;; 124 add r8=r8,r15 125 ;; 126 shr.u r10=r8,32 // now fold sum into short 127 zxt4 r11=r8 128 ;; 129 add r8=r10,r11 130 ;; 131 shr.u r10=r8,16 // yeah, keep it rolling 132 zxt2 r11=r8 133 ;; 134 add r8=r10,r11 135 ;; 136 shr.u r10=r8,16 // three times lucky 137 zxt2 r11=r8 138 ;; 139 add r8=r10,r11 140 mov r9=0xffff 141 ;; 142 andcm r8=r9,r8 143 br.ret.sptk.many b0 144END(csum_ipv6_magic) 145