Implementation of exp10 function.
authordrepper <drepper>
Tue, 9 Jun 1998 18:21:08 +0000 (18:21 +0000)
committerdrepper <drepper>
Tue, 9 Jun 1998 18:21:08 +0000 (18:21 +0000)
sysdeps/libm-i387/e_exp10.S [new file with mode: 0644]
sysdeps/libm-i387/e_exp10f.S [new file with mode: 0644]
sysdeps/libm-i387/e_exp10l.S [new file with mode: 0644]

diff --git a/sysdeps/libm-i387/e_exp10.S b/sysdeps/libm-i387/e_exp10.S
new file mode 100644 (file)
index 0000000..6bfcdbb
--- /dev/null
@@ -0,0 +1,38 @@
+/*
+ * Written by Ulrich Drepper <drepper@cygnus.com>.
+ */
+
+#include <machine/asm.h>
+
+/* 10^x = 2^(x * log2(10)) */
+ENTRY(__ieee754_exp10)
+       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.  */
+       fldl2t
+       fmulp                           /* x * log2(10) */
+       fld     %st
+       frndint                         /* int(x * log2(10)) */
+       fsubr   %st,%st(1)              /* fract(x * log2(10)) */
+       fxch
+       f2xm1                           /* 2^(fract(x * log2(10))) - 1 */
+       fld1
+       faddp                           /* 2^(fract(x * log2(10))) */
+       fscale                          /* e^x */
+       fstp    %st(1)
+       ret
+
+1:     testl   $0x200, %eax            /* Test sign.  */
+       jz      2f                      /* If positive, jump.  */
+       fstp    %st
+       fldz                            /* Set result to 0.  */
+2:     ret
+END (__ieee754_exp10)
diff --git a/sysdeps/libm-i387/e_exp10f.S b/sysdeps/libm-i387/e_exp10f.S
new file mode 100644 (file)
index 0000000..4791b99
--- /dev/null
@@ -0,0 +1,38 @@
+/*
+ * Written by Ulrich Drepper.
+ */
+
+#include <machine/asm.h>
+
+/* e^x = 2^(x * log2(10)) */
+ENTRY(__ieee754_exp10f)
+       flds    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.  */
+       fldl2t
+       fmulp                           /* x * log2(10) */
+       fld     %st
+       frndint                         /* int(x * log2(10)) */
+       fsubr   %st,%st(1)              /* fract(x * log2(10)) */
+       fxch
+       f2xm1                           /* 2^(fract(x * log2(10))) - 1 */
+       fld1
+       faddp                           /* 2^(fract(x * log2(10))) */
+       fscale                          /* e^x */
+       fstp    %st(1)
+       ret
+
+1:     testl   $0x200, %eax            /* Test sign.  */
+       jz      2f                      /* If positive, jump.  */
+       fstp    %st
+       fldz                            /* Set result to 0.  */
+2:     ret
+END (__ieee754_exp10f)
diff --git a/sysdeps/libm-i387/e_exp10l.S b/sysdeps/libm-i387/e_exp10l.S
new file mode 100644 (file)
index 0000000..71f0da7
--- /dev/null
@@ -0,0 +1,38 @@
+/*
+ * Written by Ulrich Drepper <drepper@cygnus.com>.
+ */
+
+#include <machine/asm.h>
+
+/* e^x = 2^(x * log2l(10)) */
+ENTRY(__ieee754_exp10l)
+       fldt    4(%esp)
+/* I added the following ugly construct because expl(+-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.  */
+       fldl2t
+       fmulp                           /* x * log2(10) */
+       fld     %st
+       frndint                         /* int(x * log2(10)) */
+       fsubr   %st,%st(1)              /* fract(x * log2(10)) */
+       fxch
+       f2xm1                           /* 2^(fract(x * log2(10))) - 1 */
+       fld1
+       faddp                           /* 2^(fract(x * log2(10))) */
+       fscale                          /* e^x */
+       fstp    %st(1)
+       ret
+
+1:     testl   $0x200, %eax            /* Test sign.  */
+       jz      2f                      /* If positive, jump.  */
+       fstp    %st
+       fldz                            /* Set result to 0.  */
+2:     ret
+END (__ieee754_exp10l)