epoger@google.com | ec3ed6a | 2011-07-28 14:26:00 +0000 | [diff] [blame] | 1 | |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 2 | /* |
epoger@google.com | ec3ed6a | 2011-07-28 14:26:00 +0000 | [diff] [blame] | 3 | * Copyright 2008 The Android Open Source Project |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 4 | * |
epoger@google.com | ec3ed6a | 2011-07-28 14:26:00 +0000 | [diff] [blame] | 5 | * Use of this source code is governed by a BSD-style license that can be |
| 6 | * found in the LICENSE file. |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 7 | */ |
| 8 | |
epoger@google.com | ec3ed6a | 2011-07-28 14:26:00 +0000 | [diff] [blame] | 9 | |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 10 | #include "SkFloat.h" |
reed@google.com | 4b163ed | 2012-08-07 21:35:13 +0000 | [diff] [blame] | 11 | #include "SkMathPriv.h" |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 12 | |
| 13 | #define EXP_BIAS (127+23) |
| 14 | |
| 15 | static int get_unsigned_exp(uint32_t packed) |
| 16 | { |
| 17 | return (packed << 1 >> 24); |
| 18 | } |
| 19 | |
| 20 | static unsigned get_unsigned_value(uint32_t packed) |
| 21 | { |
| 22 | return (packed << 9 >> 9) | (1 << 23); |
| 23 | } |
| 24 | |
| 25 | static int get_signed_value(int32_t packed) |
| 26 | { |
| 27 | return SkApplySign(get_unsigned_value(packed), SkExtractSign(packed)); |
| 28 | } |
| 29 | |
| 30 | ///////////////////////////////////////////////////////////////////////// |
| 31 | |
| 32 | int SkFloat::GetShift(int32_t packed, int shift) |
| 33 | { |
| 34 | if (packed == 0) |
| 35 | return 0; |
| 36 | |
| 37 | int exp = get_unsigned_exp(packed) - EXP_BIAS - shift; |
| 38 | int value = get_unsigned_value(packed); |
| 39 | |
| 40 | if (exp >= 0) |
| 41 | { |
| 42 | if (exp > 8) // overflow |
| 43 | value = SK_MaxS32; |
| 44 | else |
| 45 | value <<= exp; |
| 46 | } |
| 47 | else |
| 48 | { |
| 49 | exp = -exp; |
| 50 | if (exp > 23) // underflow |
| 51 | value = 0; |
| 52 | else |
| 53 | value >>= exp; |
| 54 | } |
| 55 | return SkApplySign(value, SkExtractSign(packed)); |
| 56 | } |
| 57 | |
| 58 | ///////////////////////////////////////////////////////////////////////////////////// |
| 59 | |
| 60 | int32_t SkFloat::SetShift(int value, int shift) |
| 61 | { |
| 62 | if (value == 0) |
| 63 | return 0; |
| 64 | |
| 65 | // record the sign and make value positive |
| 66 | int sign = SkExtractSign(value); |
| 67 | value = SkApplySign(value, sign); |
| 68 | |
| 69 | if (value >> 24) // value is too big (has more than 24 bits set) |
| 70 | { |
| 71 | int bias = 8 - SkCLZ(value); |
| 72 | SkASSERT(bias > 0 && bias < 8); |
| 73 | value >>= bias; |
| 74 | shift += bias; |
| 75 | } |
| 76 | else |
| 77 | { |
| 78 | int zeros = SkCLZ(value << 8); |
| 79 | SkASSERT(zeros >= 0 && zeros <= 23); |
| 80 | value <<= zeros; |
| 81 | shift -= zeros; |
| 82 | } |
| 83 | // now value is left-aligned to 24 bits |
| 84 | SkASSERT((value >> 23) == 1); |
| 85 | |
| 86 | shift += EXP_BIAS; |
| 87 | if (shift < 0) // underflow |
| 88 | return 0; |
| 89 | else |
| 90 | { |
| 91 | if (shift > 255) // overflow |
| 92 | { |
| 93 | shift = 255; |
| 94 | value = 0x00FFFFFF; |
| 95 | } |
| 96 | int32_t packed = sign << 31; // set the sign-bit |
| 97 | packed |= shift << 23; // store the packed exponent |
| 98 | packed |= ((unsigned)(value << 9) >> 9); // clear 24th bit of value (its implied) |
| 99 | |
| 100 | #ifdef SK_DEBUG |
| 101 | { |
| 102 | int n; |
| 103 | |
| 104 | n = SkExtractSign(packed); |
| 105 | SkASSERT(n == sign); |
| 106 | n = get_unsigned_exp(packed); |
| 107 | SkASSERT(n == shift); |
| 108 | n = get_unsigned_value(packed); |
| 109 | SkASSERT(n == value); |
| 110 | } |
| 111 | #endif |
| 112 | return packed; |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | int32_t SkFloat::Neg(int32_t packed) |
| 117 | { |
| 118 | if (packed) |
| 119 | packed = packed ^ (1 << 31); |
| 120 | return packed; |
| 121 | } |
| 122 | |
| 123 | int32_t SkFloat::Add(int32_t packed_a, int32_t packed_b) |
| 124 | { |
| 125 | if (packed_a == 0) |
| 126 | return packed_b; |
| 127 | if (packed_b == 0) |
| 128 | return packed_a; |
| 129 | |
| 130 | int exp_a = get_unsigned_exp(packed_a); |
| 131 | int exp_b = get_unsigned_exp(packed_b); |
| 132 | int exp_diff = exp_a - exp_b; |
| 133 | |
| 134 | int shift_a = 0, shift_b = 0; |
| 135 | int exp; |
| 136 | |
| 137 | if (exp_diff >= 0) |
| 138 | { |
| 139 | if (exp_diff > 24) // B is too small to contribute |
| 140 | return packed_a; |
| 141 | shift_b = exp_diff; |
| 142 | exp = exp_a; |
| 143 | } |
| 144 | else |
| 145 | { |
| 146 | exp_diff = -exp_diff; |
| 147 | if (exp_diff > 24) // A is too small to contribute |
| 148 | return packed_b; |
| 149 | shift_a = exp_diff; |
| 150 | exp = exp_b; |
| 151 | } |
| 152 | |
| 153 | int value_a = get_signed_value(packed_a) >> shift_a; |
| 154 | int value_b = get_signed_value(packed_b) >> shift_b; |
| 155 | |
| 156 | return SkFloat::SetShift(value_a + value_b, exp - EXP_BIAS); |
| 157 | } |
| 158 | |
| 159 | #include "Sk64.h" |
| 160 | |
| 161 | static inline int32_t mul24(int32_t a, int32_t b) |
| 162 | { |
| 163 | Sk64 tmp; |
| 164 | |
| 165 | tmp.setMul(a, b); |
| 166 | tmp.roundRight(24); |
| 167 | return tmp.get32(); |
| 168 | } |
| 169 | |
| 170 | int32_t SkFloat::Mul(int32_t packed_a, int32_t packed_b) |
| 171 | { |
| 172 | if (packed_a == 0 || packed_b == 0) |
| 173 | return 0; |
| 174 | |
| 175 | int exp_a = get_unsigned_exp(packed_a); |
| 176 | int exp_b = get_unsigned_exp(packed_b); |
| 177 | |
| 178 | int value_a = get_signed_value(packed_a); |
| 179 | int value_b = get_signed_value(packed_b); |
| 180 | |
| 181 | return SkFloat::SetShift(mul24(value_a, value_b), exp_a + exp_b - 2*EXP_BIAS + 24); |
| 182 | } |
| 183 | |
| 184 | int32_t SkFloat::MulInt(int32_t packed, int n) |
| 185 | { |
| 186 | return Mul(packed, SetShift(n, 0)); |
| 187 | } |
| 188 | |
| 189 | int32_t SkFloat::Div(int32_t packed_n, int32_t packed_d) |
| 190 | { |
| 191 | SkASSERT(packed_d != 0); |
| 192 | |
| 193 | if (packed_n == 0) |
| 194 | return 0; |
| 195 | |
| 196 | int exp_n = get_unsigned_exp(packed_n); |
| 197 | int exp_d = get_unsigned_exp(packed_d); |
| 198 | |
| 199 | int value_n = get_signed_value(packed_n); |
| 200 | int value_d = get_signed_value(packed_d); |
| 201 | |
| 202 | return SkFloat::SetShift(SkDivBits(value_n, value_d, 24), exp_n - exp_d - 24); |
| 203 | } |
| 204 | |
| 205 | int32_t SkFloat::DivInt(int32_t packed, int n) |
| 206 | { |
| 207 | return Div(packed, SetShift(n, 0)); |
| 208 | } |
| 209 | |
| 210 | int32_t SkFloat::Invert(int32_t packed) |
| 211 | { |
| 212 | return Div(packed, SetShift(1, 0)); |
| 213 | } |
| 214 | |
| 215 | int32_t SkFloat::Sqrt(int32_t packed) |
| 216 | { |
| 217 | if (packed < 0) |
| 218 | { |
tomhudson@google.com | 0c00f21 | 2011-12-28 14:59:50 +0000 | [diff] [blame] | 219 | SkDEBUGFAIL("can't sqrt a negative number"); |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 220 | return 0; |
| 221 | } |
| 222 | |
| 223 | int exp = get_unsigned_exp(packed); |
| 224 | int value = get_unsigned_value(packed); |
| 225 | |
| 226 | int nexp = exp - EXP_BIAS; |
| 227 | int root = SkSqrtBits(value << (nexp & 1), 26); |
| 228 | nexp >>= 1; |
| 229 | return SkFloat::SetShift(root, nexp - 11); |
| 230 | } |
| 231 | |
| 232 | #if defined _WIN32 && _MSC_VER >= 1300 // disable warning : unreachable code |
| 233 | #pragma warning ( push ) |
| 234 | #pragma warning ( disable : 4702 ) |
| 235 | #endif |
| 236 | |
| 237 | int32_t SkFloat::CubeRoot(int32_t packed) |
| 238 | { |
| 239 | sk_throw(); |
| 240 | return 0; |
| 241 | } |
| 242 | |
| 243 | #if defined _WIN32 && _MSC_VER >= 1300 |
| 244 | #pragma warning ( pop ) |
| 245 | #endif |
| 246 | |
| 247 | static inline int32_t clear_high_bit(int32_t n) |
| 248 | { |
| 249 | return ((uint32_t)(n << 1)) >> 1; |
| 250 | } |
| 251 | |
| 252 | static inline int int_sign(int32_t a, int32_t b) |
| 253 | { |
| 254 | return a > b ? 1 : (a < b ? -1 : 0); |
| 255 | } |
| 256 | |
| 257 | int SkFloat::Cmp(int32_t packed_a, int32_t packed_b) |
| 258 | { |
| 259 | packed_a = SkApplySign(clear_high_bit(packed_a), SkExtractSign(packed_a)); |
| 260 | packed_b = SkApplySign(clear_high_bit(packed_b), SkExtractSign(packed_b)); |
| 261 | |
| 262 | return int_sign(packed_a, packed_b); |
| 263 | } |
| 264 | |
| 265 | ///////////////////////////////////////////////////////////////////////////////////// |
| 266 | ///////////////////////////////////////////////////////////////////////////////////// |
| 267 | |
| 268 | #ifdef SK_DEBUG |
| 269 | |
| 270 | #include "SkRandom.h" |
reed@google.com | 7886ad3 | 2012-06-11 21:21:26 +0000 | [diff] [blame] | 271 | #include "SkFloatingPoint.h" |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 272 | |
| 273 | void SkFloat::UnitTest() |
| 274 | { |
robertphillips@google.com | 385afd8 | 2013-12-19 23:17:56 +0000 | [diff] [blame] | 275 | #if 0 // def SK_SUPPORT_UNITTEST |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 276 | SkFloat a, b, c, d; |
| 277 | int n; |
| 278 | |
| 279 | a.setZero(); |
| 280 | n = a.getInt(); |
| 281 | SkASSERT(n == 0); |
| 282 | |
| 283 | b.setInt(5); |
| 284 | n = b.getInt(); |
| 285 | SkASSERT(n == 5); |
| 286 | |
| 287 | c.setInt(-3); |
| 288 | n = c.getInt(); |
| 289 | SkASSERT(n == -3); |
| 290 | |
| 291 | d.setAdd(c, b); |
rmistry@google.com | fbfcd56 | 2012-08-23 18:09:54 +0000 | [diff] [blame] | 292 | SkDebugf("SkFloat: %d + %d = %d\n", c.getInt(), b.getInt(), d.getInt()); |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 293 | |
commit-bot@chromium.org | e0e7cfe | 2013-09-09 20:09:12 +0000 | [diff] [blame] | 294 | SkRandom rand; |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 295 | |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 296 | int i; |
| 297 | for (i = 0; i < 1000; i++) |
| 298 | { |
| 299 | float fa, fb; |
| 300 | int aa = rand.nextS() >> 14; |
| 301 | int bb = rand.nextS() >> 14; |
| 302 | a.setInt(aa); |
| 303 | b.setInt(bb); |
| 304 | SkASSERT(a.getInt() == aa); |
| 305 | SkASSERT(b.getInt() == bb); |
| 306 | |
| 307 | c.setAdd(a, b); |
| 308 | int cc = c.getInt(); |
| 309 | SkASSERT(cc == aa + bb); |
| 310 | |
| 311 | c.setSub(a, b); |
| 312 | cc = c.getInt(); |
| 313 | SkASSERT(cc == aa - bb); |
| 314 | |
| 315 | aa >>= 5; |
| 316 | bb >>= 5; |
| 317 | a.setInt(aa); |
| 318 | b.setInt(bb); |
| 319 | c.setMul(a, b); |
| 320 | cc = c.getInt(); |
| 321 | SkASSERT(cc == aa * bb); |
| 322 | ///////////////////////////////////// |
| 323 | |
| 324 | aa = rand.nextS() >> 11; |
| 325 | a.setFixed(aa); |
| 326 | cc = a.getFixed(); |
| 327 | SkASSERT(aa == cc); |
| 328 | |
| 329 | bb = rand.nextS() >> 11; |
| 330 | b.setFixed(bb); |
| 331 | cc = b.getFixed(); |
| 332 | SkASSERT(bb == cc); |
| 333 | |
| 334 | cc = SkFixedMul(aa, bb); |
| 335 | c.setMul(a, b); |
| 336 | SkFixed dd = c.getFixed(); |
| 337 | int diff = cc - dd; |
| 338 | SkASSERT(SkAbs32(diff) <= 1); |
| 339 | |
| 340 | fa = (float)aa / 65536.0f; |
| 341 | fb = (float)bb / 65536.0f; |
| 342 | a.assertEquals(fa); |
| 343 | b.assertEquals(fb); |
| 344 | fa = a.getFloat(); |
| 345 | fb = b.getFloat(); |
| 346 | |
| 347 | c.assertEquals(fa * fb, 1); |
| 348 | |
| 349 | c.setDiv(a, b); |
| 350 | cc = SkFixedDiv(aa, bb); |
| 351 | dd = c.getFixed(); |
| 352 | diff = cc - dd; |
| 353 | SkASSERT(SkAbs32(diff) <= 3); |
| 354 | |
| 355 | c.assertEquals(fa / fb, 1); |
| 356 | |
| 357 | SkASSERT((aa == bb) == (a == b)); |
| 358 | SkASSERT((aa != bb) == (a != b)); |
| 359 | SkASSERT((aa < bb) == (a < b)); |
| 360 | SkASSERT((aa <= bb) == (a <= b)); |
| 361 | SkASSERT((aa > bb) == (a > b)); |
| 362 | SkASSERT((aa >= bb) == (a >= b)); |
| 363 | |
| 364 | if (aa < 0) |
| 365 | { |
| 366 | aa = -aa; |
| 367 | fa = -fa; |
| 368 | } |
| 369 | a.setFixed(aa); |
| 370 | c.setSqrt(a); |
| 371 | cc = SkFixedSqrt(aa); |
| 372 | dd = c.getFixed(); |
| 373 | SkASSERT(dd == cc); |
| 374 | |
| 375 | c.assertEquals(sk_float_sqrt(fa), 2); |
| 376 | |
| 377 | // cuberoot |
| 378 | #if 0 |
| 379 | a.setInt(1); |
| 380 | a.cubeRoot(); |
| 381 | a.assertEquals(1.0f, 0); |
| 382 | a.setInt(8); |
| 383 | a.cubeRoot(); |
| 384 | a.assertEquals(2.0f, 0); |
| 385 | a.setInt(27); |
| 386 | a.cubeRoot(); |
| 387 | a.assertEquals(3.0f, 0); |
| 388 | #endif |
| 389 | } |
| 390 | #endif |
reed@android.com | 8a1c16f | 2008-12-17 15:59:43 +0000 | [diff] [blame] | 391 | } |
| 392 | |
| 393 | #endif |