60 lines
1.1 KiB
C
60 lines
1.1 KiB
C
#include "ultra64.h"
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#include "global.h"
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static const du P[] = {
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{ 0x3FF00000, 0x00000000 }, { 0xBFC55554, 0xBC83656D }, { 0x3F8110ED, 0x3804C2A0 },
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{ 0xBF29F6FF, 0xEEA56814 }, { 0x3EC5DBDF, 0x0E314BFE },
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};
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static const du rpi = { 0x3FD45F30, 0x6DC9C883 };
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static const du pihi = { 0x400921FB, 0x50000000 };
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static const du pilo = { 0x3E6110B4, 0x611A6263 };
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static const fu zero = { 0x00000000 };
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f32 cosf(f32 x) {
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f32 absx;
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f64 dx;
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f64 xSq;
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f64 polyApprox;
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f64 dn;
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s32 n;
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f64 result;
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s32 ix = *(s32*)&x;
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s32 xpt = (ix >> 22);
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xpt &= 0x1FF;
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if (xpt < 0x136) {
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absx = (x > 0) ? x : -x;
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dx = absx;
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dn = dx * rpi.d + 0.5;
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n = ROUND(dn);
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dn = n;
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dn -= 0.5;
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dx -= dn * pihi.d;
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dx -= dn * pilo.d;
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xSq = SQ(dx);
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polyApprox = ((P[4].d * xSq + P[3].d) * xSq + P[2].d) * xSq + P[1].d;
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result = dx + (dx * xSq) * polyApprox;
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if (!(n & 1)) {
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return (f32)result;
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}
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return -(f32)result;
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}
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if (x != x) {
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return __libm_qnan_f;
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}
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return zero.f;
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}
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