/*      $OpenBSD: e_acos.S,v 1.6 2018/07/03 22:43:34 mortimer Exp $ */
/*
 * Written by J.T. Conklin <jtc@NetBSD.org>.
 * Public domain.
 */

#include <machine/asm.h>

#include "abi.h"

/* acos = atan (sqrt(1 - x^2) / x) */
ENTRY(acos)
        RETGUARD_SETUP(acos, r11)
        XMM_ONE_ARG_DOUBLE_PROLOGUE
        fldl    ARG_DOUBLE_ONE          /* x */
        fld     %st(0)
        fmul    %st(0)                  /* x^2 */
        fld1                            
        fsubp                           /* 1 - x^2 */
        fsqrt                           /* sqrt (1 - x^2) */
        fxch    %st(1)
        fpatan
        XMM_DOUBLE_EPILOGUE
        RETGUARD_CHECK(acos, r11)
        ret
END(acos)