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41 lines
723 B
C
41 lines
723 B
C
/*
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* Written by J.T. Conklin <jtc@netbsd.org>.
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* Public domain.
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*/
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#include <math.h>
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float
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acosf (float x)
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{
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float res;
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/* acosl = atanl (sqrtl(1 - x^2) / x) */
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asm ( "fld %%st\n\t"
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"fmul %%st(0)\n\t" /* x^2 */
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"fld1\n\t"
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"fsubp\n\t" /* 1 - x^2 */
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"fsqrt\n\t" /* sqrtl (1 - x^2) */
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"fxch %%st(1)\n\t"
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"fpatan"
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: "=t" (res) : "0" (x) : "st(1)");
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return res;
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}
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double
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acos (double x)
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{
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double res;
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/* acosl = atanl (sqrtl(1 - x^2) / x) */
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asm ( "fld %%st\n\t"
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"fmul %%st(0)\n\t" /* x^2 */
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"fld1\n\t"
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"fsubp\n\t" /* 1 - x^2 */
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"fsqrt\n\t" /* sqrtl (1 - x^2) */
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"fxch %%st(1)\n\t"
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"fpatan"
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: "=t" (res) : "0" (x) : "st(1)");
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return res;
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}
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