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-rw-r--r--sysdeps/libm-i387/e_log.S52
1 files changed, 48 insertions, 4 deletions
diff --git a/sysdeps/libm-i387/e_log.S b/sysdeps/libm-i387/e_log.S
index 2a51d7520c..43d430332c 100644
--- a/sysdeps/libm-i387/e_log.S
+++ b/sysdeps/libm-i387/e_log.S
@@ -1,15 +1,59 @@
 /*
  * Written by J.T. Conklin <jtc@netbsd.org>.
  * Public domain.
+ *
+ * Changed to use fyl2xp1 for values near 1, <drepper@cygnus.com>.
  */
 
 #include <machine/asm.h>
 
 RCSID("$NetBSD: e_log.S,v 1.4 1995/05/08 23:48:39 jtc Exp $")
 
+#ifdef __ELF__
+	.section .rodata
+#else
+	.text
+#endif
+	.align ALIGNARG(4)
+	ASM_TYPE_DIRECTIVE(one,@object)
+one:	.double 1.0
+	ASM_SIZE_DIRECTIVE(one)
+	/* It is not important that this constant is precise.  It is only
+	   a value which is known to be on the safe side for using the
+	   fyl2xp1 instruction.  */
+	ASM_TYPE_DIRECTIVE(limit,@object)
+limit:	.double 0.29
+	ASM_SIZE_DIRECTIVE(limit)
+
+
+#ifdef PIC
+#define MO(op) op##@GOTOFF(%edx)
+#else
+#define MO(op) op
+#endif
+
+	.text
 ENTRY(__ieee754_log)
-	fldln2
-	fldl	4(%esp)
-	fyl2x
+	fldln2			// log(2)
+	fldl	4(%esp)		// x : log(2)
+#ifdef PIC
+	call	1f
+1:	popl	%edx
+	addl	$_GLOBAL_OFFSET_TABLE_+[.-1b], %edx
+#endif
+	fld	%st		// x : x : log(2)
+	fsubl	MO(one)		// x-1 : x : log(2)
+	fld	%st		// x-1 : x-1 : x : log(2)
+	fabs			// |x-1| : x-1 : x : log(2)
+	fcompl	MO(limit)	// x-1 : x : log(2)
+	fnstsw			// x-1 : x : log(2)
+	sahf
+	ja	2f
+	fstp	%st(1)		// x-1 : log(2)
+	fyl2xp1			// log(x)
+	ret
+
+2:	fincstp			// x : log(2)
+	fyl2x			// log(x)
 	ret
-PSEUDO_END (__ieee754_log)
+END (__ieee754_log)