| 1 | /* |
| 2 | * Common Trace Format |
| 3 | * |
| 4 | * Floating point read/write functions. |
| 5 | * |
| 6 | * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 7 | * |
| 8 | * Reference: ISO C99 standard 5.2.4 |
| 9 | * |
| 10 | * Dual LGPL v2.1/GPL v2 license. |
| 11 | */ |
| 12 | |
| 13 | #include <ctf/ctf-types.h> |
| 14 | #include <glib.h> |
| 15 | #include <endian.h> |
| 16 | |
| 17 | /* |
| 18 | * Aliasing float/double and unsigned long is not strictly permitted by strict |
| 19 | * aliasing, but in practice type prunning is well supported, and this permits |
| 20 | * us to use per-word read/writes rather than per-byte. |
| 21 | */ |
| 22 | |
| 23 | #if defined(__GNUC__) || defined(__MINGW32__) || defined(_MSC_VER) |
| 24 | #define HAS_TYPE_PRUNING |
| 25 | #endif |
| 26 | |
| 27 | union floatIEEE754 { |
| 28 | float v; |
| 29 | #ifdef HAS_TYPE_PRUNING |
| 30 | unsigned long bits[(sizeof(float) + sizeof(unsigned long) - 1) / sizeof(unsigned long)]; |
| 31 | #else |
| 32 | unsigned char bits[sizeof(float)]; |
| 33 | #endif |
| 34 | }; |
| 35 | |
| 36 | union doubleIEEE754 { |
| 37 | double v; |
| 38 | #ifdef HAS_TYPE_PRUNING |
| 39 | unsigned long bits[(sizeof(double) + sizeof(unsigned long) - 1) / sizeof(unsigned long)]; |
| 40 | #else |
| 41 | unsigned char bits[sizeof(double)]; |
| 42 | #endif |
| 43 | }; |
| 44 | |
| 45 | double float_read(const uint8_t *ptr, size_t len, int byte_order) |
| 46 | { |
| 47 | int rbo = (byte_order != __FLOAT_WORD_ORDER); /* reverse byte order */ |
| 48 | |
| 49 | switch (len) { |
| 50 | case 32: |
| 51 | { |
| 52 | union floatIEEE754 u; |
| 53 | uint32_t tmp; |
| 54 | |
| 55 | if (!rbo) |
| 56 | return (double) *(const float *) ptr; |
| 57 | /* |
| 58 | * Need to reverse byte order. Read the opposite from our |
| 59 | * architecture. |
| 60 | */ |
| 61 | if (__FLOAT_WORD_ORDER == LITTLE_ENDIAN) { |
| 62 | /* Read big endian */ |
| 63 | tmp = bitfield_unsigned_read(ptr, 0, 1, BIG_ENDIAN); |
| 64 | bitfield_unsigned_write(&u.bits, 31, 1, LITTLE_ENDIAN, |
| 65 | tmp); |
| 66 | tmp = bitfield_unsigned_read(ptr, 1, 8, BIG_ENDIAN); |
| 67 | bitfield_unsigned_write(&u.bits, 23, 8, LITTLE_ENDIAN, |
| 68 | tmp); |
| 69 | tmp = bitfield_unsigned_read(ptr, 9, 23, BIG_ENDIAN); |
| 70 | bitfield_unsigned_write(&u.bits, 0, 23, LITTLE_ENDIAN, |
| 71 | tmp); |
| 72 | } else { |
| 73 | /* Read little endian */ |
| 74 | tmp = bitfield_unsigned_read(ptr, 31, 1, LITTLE_ENDIAN); |
| 75 | bitfield_unsigned_write(&u.bits, 0, 1, BIG_ENDIAN, |
| 76 | tmp); |
| 77 | tmp = bitfield_unsigned_read(ptr, 23, 8, LITTLE_ENDIAN); |
| 78 | bitfield_unsigned_write(&u.bits, 1, 8, BIG_ENDIAN, |
| 79 | tmp); |
| 80 | tmp = bitfield_unsigned_read(ptr, 0, 23, LITTLE_ENDIAN); |
| 81 | bitfield_unsigned_write(&u.bits, 9, 23, BIG_ENDIAN, |
| 82 | tmp); |
| 83 | } |
| 84 | return (double) u.v; |
| 85 | } |
| 86 | case 64: |
| 87 | { |
| 88 | union doubleIEEE754 u; |
| 89 | uint64_t tmp; |
| 90 | |
| 91 | if (!rbo) |
| 92 | return (double) *(const double *) ptr; |
| 93 | /* |
| 94 | * Need to reverse byte order. Read the opposite from our |
| 95 | * architecture. |
| 96 | */ |
| 97 | if (__FLOAT_WORD_ORDER == LITTLE_ENDIAN) { |
| 98 | /* Read big endian */ |
| 99 | tmp = bitfield_unsigned_read(ptr, 0, 1, BIG_ENDIAN); |
| 100 | bitfield_unsigned_write(&u.bits, 63, 1, LITTLE_ENDIAN, |
| 101 | tmp); |
| 102 | tmp = bitfield_unsigned_read(ptr, 1, 11, BIG_ENDIAN); |
| 103 | bitfield_unsigned_write(&u.bits, 52, 11, LITTLE_ENDIAN, |
| 104 | tmp); |
| 105 | tmp = bitfield_unsigned_read(ptr, 12, 52, BIG_ENDIAN); |
| 106 | bitfield_unsigned_write(&u.bits, 0, 52, LITTLE_ENDIAN, |
| 107 | tmp); |
| 108 | } else { |
| 109 | /* Read little endian */ |
| 110 | tmp = bitfield_unsigned_read(ptr, 63, 1, LITTLE_ENDIAN); |
| 111 | bitfield_unsigned_write(&u.bits, 0, 1, BIG_ENDIAN, |
| 112 | tmp); |
| 113 | tmp = bitfield_unsigned_read(ptr, 52, 11, LITTLE_ENDIAN); |
| 114 | bitfield_unsigned_write(&u.bits, 1, 11, BIG_ENDIAN, |
| 115 | tmp); |
| 116 | tmp = bitfield_unsigned_read(ptr, 0, 52, LITTLE_ENDIAN); |
| 117 | bitfield_unsigned_write(&u.bits, 12, 52, BIG_ENDIAN, |
| 118 | tmp); |
| 119 | } |
| 120 | return u.v; |
| 121 | } |
| 122 | default: |
| 123 | printf("float read unavailable for size %u\n", len); |
| 124 | assert(0); |
| 125 | } |
| 126 | } |
| 127 | |
| 128 | size_t float_write(uint8_t *ptr, size_t len, int byte_order, double v) |
| 129 | { |
| 130 | int rbo = (byte_order != __FLOAT_WORD_ORDER); /* reverse byte order */ |
| 131 | |
| 132 | if (!ptr) |
| 133 | goto end; |
| 134 | |
| 135 | switch (len) { |
| 136 | case 32: |
| 137 | { |
| 138 | union floatIEEE754 u; |
| 139 | uint32_t tmp; |
| 140 | |
| 141 | if (!rbo) { |
| 142 | *(float *) ptr = (float) v; |
| 143 | break; |
| 144 | } |
| 145 | u.v = v; |
| 146 | /* |
| 147 | * Need to reverse byte order. Write the opposite from our |
| 148 | * architecture. |
| 149 | */ |
| 150 | if (__FLOAT_WORD_ORDER == LITTLE_ENDIAN) { |
| 151 | /* Write big endian */ |
| 152 | tmp = bitfield_unsigned_read(ptr, 31, 1, LITTLE_ENDIAN); |
| 153 | bitfield_unsigned_write(&u.bits, 0, 1, BIG_ENDIAN, |
| 154 | tmp); |
| 155 | tmp = bitfield_unsigned_read(ptr, 23, 8, LITTLE_ENDIAN); |
| 156 | bitfield_unsigned_write(&u.bits, 1, 8, BIG_ENDIAN, |
| 157 | tmp); |
| 158 | tmp = bitfield_unsigned_read(ptr, 0, 23, LITTLE_ENDIAN); |
| 159 | bitfield_unsigned_write(&u.bits, 9, 23, BIG_ENDIAN, |
| 160 | tmp); |
| 161 | } else { |
| 162 | /* Write little endian */ |
| 163 | tmp = bitfield_unsigned_read(ptr, 0, 1, BIG_ENDIAN); |
| 164 | bitfield_unsigned_write(&u.bits, 31, 1, LITTLE_ENDIAN, |
| 165 | tmp); |
| 166 | tmp = bitfield_unsigned_read(ptr, 1, 8, BIG_ENDIAN); |
| 167 | bitfield_unsigned_write(&u.bits, 23, 8, LITTLE_ENDIAN, |
| 168 | tmp); |
| 169 | tmp = bitfield_unsigned_read(ptr, 9, 23, BIG_ENDIAN); |
| 170 | bitfield_unsigned_write(&u.bits, 0, 23, LITTLE_ENDIAN, |
| 171 | tmp); |
| 172 | } |
| 173 | break; |
| 174 | } |
| 175 | case 64: |
| 176 | { |
| 177 | union doubleIEEE754 u; |
| 178 | uint64_t tmp; |
| 179 | |
| 180 | if (!rbo) { |
| 181 | *(double *) ptr = v; |
| 182 | break; |
| 183 | } |
| 184 | u.v = v; |
| 185 | /* |
| 186 | * Need to reverse byte order. Write the opposite from our |
| 187 | * architecture. |
| 188 | */ |
| 189 | if (__FLOAT_WORD_ORDER == LITTLE_ENDIAN) { |
| 190 | /* Write big endian */ |
| 191 | tmp = bitfield_unsigned_read(ptr, 63, 1, LITTLE_ENDIAN); |
| 192 | bitfield_unsigned_write(&u.bits, 0, 1, BIG_ENDIAN, |
| 193 | tmp); |
| 194 | tmp = bitfield_unsigned_read(ptr, 52, 11, LITTLE_ENDIAN); |
| 195 | bitfield_unsigned_write(&u.bits, 1, 11, BIG_ENDIAN, |
| 196 | tmp); |
| 197 | tmp = bitfield_unsigned_read(ptr, 0, 52, LITTLE_ENDIAN); |
| 198 | bitfield_unsigned_write(&u.bits, 12, 52, BIG_ENDIAN, |
| 199 | tmp); |
| 200 | } else { |
| 201 | /* Write little endian */ |
| 202 | tmp = bitfield_unsigned_read(ptr, 0, 1, BIG_ENDIAN); |
| 203 | bitfield_unsigned_write(&u.bits, 63, 1, LITTLE_ENDIAN, |
| 204 | tmp); |
| 205 | tmp = bitfield_unsigned_read(ptr, 1, 11, BIG_ENDIAN); |
| 206 | bitfield_unsigned_write(&u.bits, 52, 11, LITTLE_ENDIAN, |
| 207 | tmp); |
| 208 | tmp = bitfield_unsigned_read(ptr, 12, 52, BIG_ENDIAN); |
| 209 | bitfield_unsigned_write(&u.bits, 0, 52, LITTLE_ENDIAN, |
| 210 | tmp); |
| 211 | } |
| 212 | break; |
| 213 | } |
| 214 | default: |
| 215 | printf("float write unavailable for size %u\n", len); |
| 216 | assert(0); |
| 217 | } |
| 218 | end: |
| 219 | return len; |
| 220 | } |