/* * Written by J.T. Conklin . * Public domain. */ #include #include DEFINE_DBL_MIN #ifdef PIC # define MO(op) op##@GOTOFF(%ecx) #else # define MO(op) op #endif .text /* e^x = 2^(x * log2(e)) */ ENTRY(__ieee754_exp) #ifdef PIC LOAD_PIC_REG (cx) #endif fldl 4(%esp) /* I added the following ugly construct because exp(+-Inf) resulted in NaN. The ugliness results from the bright minds at Intel. For the i686 the code can be written better. -- drepper@cygnus.com. */ fxam /* Is NaN or +-Inf? */ fstsw %ax movb $0x45, %dh andb %ah, %dh cmpb $0x05, %dh je 1f /* Is +-Inf, jump. */ fldl2e fmulp /* x * log2(e) */ fld %st frndint /* int(x * log2(e)) */ fsubr %st,%st(1) /* fract(x * log2(e)) */ fxch f2xm1 /* 2^(fract(x * log2(e))) - 1 */ fld1 faddp /* 2^(fract(x * log2(e))) */ fscale /* e^x */ fstp %st(1) DBL_NARROW_EVAL_UFLOW_NONNEG_NAN ret 1: testl $0x200, %eax /* Test sign. */ jz 2f /* If positive, jump. */ fstp %st fldz /* Set result to 0. */ 2: ret END (__ieee754_exp) ENTRY(__exp_finite) #ifdef PIC LOAD_PIC_REG (cx) #endif fldl2e fmull 4(%esp) /* x * log2(e) */ fld %st frndint /* int(x * log2(e)) */ fsubr %st,%st(1) /* fract(x * log2(e)) */ fxch f2xm1 /* 2^(fract(x * log2(e))) - 1 */ fld1 faddp /* 2^(fract(x * log2(e))) */ fscale /* e^x */ fstp %st(1) DBL_NARROW_EVAL_UFLOW_NONNEG ret END(__exp_finite)