1 /*********************************************************************** 2 * * 3 * This software is part of the ast package * 4 * Copyright (c) 1985-2007 AT&T Knowledge Ventures * 5 * and is licensed under the * 6 * Common Public License, Version 1.0 * 7 * by AT&T Knowledge Ventures * 8 * * 9 * A copy of the License is available at * 10 * http://www.opensource.org/licenses/cpl1.0.txt * 11 * (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) * 12 * * 13 * Information and Software Systems Research * 14 * AT&T Research * 15 * Florham Park NJ * 16 * * 17 * Glenn Fowler <gsf@research.att.com> * 18 * David Korn <dgk@research.att.com> * 19 * Phong Vo <kpv@research.att.com> * 20 * * 21 ***********************************************************************/ 22 #pragma prototyped 23 /* 24 * Glenn Fowler 25 * AT&T Research 26 * 27 * internal representation conversion support 28 */ 29 30 #include <ast.h> 31 #include <swap.h> 32 33 /* 34 * swap n bytes according to op 35 * from==to is ok 36 */ 37 38 void* 39 swapmem(int op, const void* from, void* to, register size_t n) 40 { 41 register char* f = (char*)from; 42 register char* t = (char*)to; 43 register int c; 44 45 switch (op & (n - 1)) 46 { 47 case 0: 48 if (t != f) 49 memcpy(t, f, n); 50 break; 51 case 1: 52 for (n >>= 1; n--; f += 2, t += 2) 53 { 54 c = f[0]; t[0] = f[1]; t[1] = c; 55 } 56 break; 57 case 2: 58 for (n >>= 2; n--; f += 4, t += 4) 59 { 60 c = f[0]; t[0] = f[2]; t[2] = c; 61 c = f[1]; t[1] = f[3]; t[3] = c; 62 } 63 break; 64 case 3: 65 for (n >>= 2; n--; f += 4, t += 4) 66 { 67 c = f[0]; t[0] = f[3]; t[3] = c; 68 c = f[1]; t[1] = f[2]; t[2] = c; 69 } 70 break; 71 case 4: 72 for (n >>= 3; n--; f += 8, t += 8) 73 { 74 c = f[0]; t[0] = f[4]; t[4] = c; 75 c = f[1]; t[1] = f[5]; t[5] = c; 76 c = f[2]; t[2] = f[6]; t[6] = c; 77 c = f[3]; t[3] = f[7]; t[7] = c; 78 } 79 break; 80 case 5: 81 for (n >>= 3; n--; f += 8, t += 8) 82 { 83 c = f[0]; t[0] = f[5]; t[5] = c; 84 c = f[1]; t[1] = f[4]; t[4] = c; 85 c = f[2]; t[2] = f[7]; t[7] = c; 86 c = f[3]; t[3] = f[6]; t[6] = c; 87 } 88 break; 89 case 6: 90 for (n >>= 3; n--; f += 8, t += 8) 91 { 92 c = f[0]; t[0] = f[6]; t[6] = c; 93 c = f[1]; t[1] = f[7]; t[7] = c; 94 c = f[2]; t[2] = f[4]; t[4] = c; 95 c = f[3]; t[3] = f[5]; t[5] = c; 96 } 97 break; 98 case 7: 99 for (n >>= 3; n--; f += 8, t += 8) 100 { 101 c = f[0]; t[0] = f[7]; t[7] = c; 102 c = f[1]; t[1] = f[6]; t[6] = c; 103 c = f[2]; t[2] = f[5]; t[5] = c; 104 c = f[3]; t[3] = f[4]; t[4] = c; 105 } 106 break; 107 } 108 return to; 109 } 110