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1 #include <math.h> | 1 #include <math.h> |
2 #include <stdint.h> | 2 #include <stdint.h> |
3 | 3 |
4 float fmodf(float x, float y) | 4 float fmodf(float x, float y) { |
5 { | 5 union { |
6 » union {float f; uint32_t i;} ux = {x}, uy = {y}; | 6 float f; |
7 » int ex = ux.i>>23 & 0xff; | 7 uint32_t i; |
8 » int ey = uy.i>>23 & 0xff; | 8 } ux = {x}, uy = {y}; |
9 » uint32_t sx = ux.i & 0x80000000; | 9 int ex = ux.i >> 23 & 0xff; |
10 » uint32_t i; | 10 int ey = uy.i >> 23 & 0xff; |
11 » uint32_t uxi = ux.i; | 11 uint32_t sx = ux.i & 0x80000000; |
| 12 uint32_t i; |
| 13 uint32_t uxi = ux.i; |
12 | 14 |
13 » if (uy.i<<1 == 0 || isnan(y) || ex == 0xff) | 15 if (uy.i << 1 == 0 || isnan(y) || ex == 0xff) |
14 » » return (x*y)/(x*y); | 16 return (x * y) / (x * y); |
15 » if (uxi<<1 <= uy.i<<1) { | 17 if (uxi << 1 <= uy.i << 1) { |
16 » » if (uxi<<1 == uy.i<<1) | 18 if (uxi << 1 == uy.i << 1) |
17 » » » return 0*x; | 19 return 0 * x; |
18 » » return x; | 20 return x; |
19 » } | 21 } |
20 | 22 |
21 » /* normalize x and y */ | 23 /* normalize x and y */ |
22 » if (!ex) { | 24 if (!ex) { |
23 » » for (i = uxi<<9; i>>31 == 0; ex--, i <<= 1); | 25 for (i = uxi << 9; i >> 31 == 0; ex--, i <<= 1) |
24 » » uxi <<= -ex + 1; | 26 ; |
25 » } else { | 27 uxi <<= -ex + 1; |
26 » » uxi &= -1U >> 9; | 28 } else { |
27 » » uxi |= 1U << 23; | 29 uxi &= -1U >> 9; |
28 » } | 30 uxi |= 1U << 23; |
29 » if (!ey) { | 31 } |
30 » » for (i = uy.i<<9; i>>31 == 0; ey--, i <<= 1); | 32 if (!ey) { |
31 » » uy.i <<= -ey + 1; | 33 for (i = uy.i << 9; i >> 31 == 0; ey--, i <<= 1) |
32 » } else { | 34 ; |
33 » » uy.i &= -1U >> 9; | 35 uy.i <<= -ey + 1; |
34 » » uy.i |= 1U << 23; | 36 } else { |
35 » } | 37 uy.i &= -1U >> 9; |
| 38 uy.i |= 1U << 23; |
| 39 } |
36 | 40 |
37 » /* x mod y */ | 41 /* x mod y */ |
38 » for (; ex > ey; ex--) { | 42 for (; ex > ey; ex--) { |
39 » » i = uxi - uy.i; | 43 i = uxi - uy.i; |
40 » » if (i >> 31 == 0) { | 44 if (i >> 31 == 0) { |
41 » » » if (i == 0) | 45 if (i == 0) |
42 » » » » return 0*x; | 46 return 0 * x; |
43 » » » uxi = i; | 47 uxi = i; |
44 » » } | 48 } |
45 » » uxi <<= 1; | 49 uxi <<= 1; |
46 » } | 50 } |
47 » i = uxi - uy.i; | 51 i = uxi - uy.i; |
48 » if (i >> 31 == 0) { | 52 if (i >> 31 == 0) { |
49 » » if (i == 0) | 53 if (i == 0) |
50 » » » return 0*x; | 54 return 0 * x; |
51 » » uxi = i; | 55 uxi = i; |
52 » } | 56 } |
53 » for (; uxi>>23 == 0; uxi <<= 1, ex--); | 57 for (; uxi >> 23 == 0; uxi <<= 1, ex--) |
| 58 ; |
54 | 59 |
55 » /* scale result up */ | 60 /* scale result up */ |
56 » if (ex > 0) { | 61 if (ex > 0) { |
57 » » uxi -= 1U << 23; | 62 uxi -= 1U << 23; |
58 » » uxi |= (uint32_t)ex << 23; | 63 uxi |= (uint32_t)ex << 23; |
59 » } else { | 64 } else { |
60 » » uxi >>= -ex + 1; | 65 uxi >>= -ex + 1; |
61 » } | 66 } |
62 » uxi |= sx; | 67 uxi |= sx; |
63 » ux.i = uxi; | 68 ux.i = uxi; |
64 » return ux.f; | 69 return ux.f; |
65 } | 70 } |
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