diff options
Diffstat (limited to 'libpsn00b/psxgte/isin.c')
| -rw-r--r-- | libpsn00b/psxgte/isin.c | 50 |
1 files changed, 31 insertions, 19 deletions
diff --git a/libpsn00b/psxgte/isin.c b/libpsn00b/psxgte/isin.c index 79e2970..a0397bd 100644 --- a/libpsn00b/psxgte/isin.c +++ b/libpsn00b/psxgte/isin.c @@ -1,34 +1,46 @@ -/* Based on isin_S4 implementation from coranac: - * http://www.coranac.com/2009/07/sines/ +/* + * PSn00bSDK (incomplete) trigonometry library + * (C) 2019-2022 Lameguy64, spicyjpeg - MPL licensed * + * Based on isin_S4 implementation from coranac: + * https://www.coranac.com/2009/07/sines */ -#define qN 10 -#define qA 12 -#define B 19900 -#define C 3516 +#define qN_l 10 +#define qN_h 15 +#define qA 12 +#define B 19900 +#define C 3516 -int isin(int x) { - - int c, x2, y; +static inline int _isin(int qN, int x) { + int c, x2, y; - c= x<<(30-qN); // Semi-circle info into carry. - x -= 1<<qN; // sine -> cosine calc + c = x << (30 - qN); // Semi-circle info into carry. + x -= 1 << qN; // sine -> cosine calc - x= x<<(31-qN); // Mask with PI - x= x>>(31-qN); // Note: SIGNED shift! (to qN) + x <<= (31 - qN); // Mask with PI + x >>= (31 - qN); // Note: SIGNED shift! (to qN) + x *= x; + x >>= (2 * qN - 14); // x=x^2 To Q14 - x= x*x>>(2*qN-14); // x=x^2 To Q14 + y = B - (x * C >> 14); // B - x^2*C + y = (1 << qA) - (x * y >> 16); // A - x^2*(B-x^2*C) - y= B - (x*C>>14); // B - x^2*C - y= (1<<qA)-(x*y>>16); // A - x^2*(B-x^2*C) - - return c>=0 ? y : -y; + return (c >= 0) ? y : (-y); +} +int isin(int x) { + return _isin(qN_l, x); } int icos(int x) { + return _isin(qN_l, x + (1 << qN_l)); +} - return isin( x+1024 ); +int hisin(int x) { + return _isin(qN_h, x); +} +int hicos(int x) { + return _isin(qN_h, x + (1 << qN_h)); } |