Module Name: src
Committed By: isaki
Date: Fri Apr 19 14:05:12 UTC 2013
Modified Files:
src/sys/arch/m68k/fpe: fpu_hyperb.c
Log Message:
Implement a hyperbolic arctangent (FATANH).
To generate a diff of this commit:
cvs rdiff -u -r1.9 -r1.10 src/sys/arch/m68k/fpe/fpu_hyperb.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/m68k/fpe/fpu_hyperb.c
diff -u src/sys/arch/m68k/fpe/fpu_hyperb.c:1.9 src/sys/arch/m68k/fpe/fpu_hyperb.c:1.10
--- src/sys/arch/m68k/fpe/fpu_hyperb.c:1.9 Fri Apr 19 13:31:11 2013
+++ src/sys/arch/m68k/fpe/fpu_hyperb.c Fri Apr 19 14:05:12 2013
@@ -1,4 +1,4 @@
-/* $NetBSD: fpu_hyperb.c,v 1.9 2013/04/19 13:31:11 isaki Exp $ */
+/* $NetBSD: fpu_hyperb.c,v 1.10 2013/04/19 14:05:12 isaki Exp $ */
/*
* Copyright (c) 1995 Ken Nakata
@@ -57,7 +57,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: fpu_hyperb.c,v 1.9 2013/04/19 13:31:11 isaki Exp $");
+__KERNEL_RCSID(0, "$NetBSD: fpu_hyperb.c,v 1.10 2013/04/19 14:05:12 isaki Exp $");
#include "fpu_emulate.h"
@@ -67,11 +67,73 @@ __KERNEL_RCSID(0, "$NetBSD: fpu_hyperb.c
* fpu_atanh(), fpu_cosh(), fpu_sinh(), and fpu_tanh()
*/
+/*
+ * 1 1 + x
+ * atanh(x) = ---*log(-------)
+ * 2 1 - x
+ */
struct fpn *
fpu_atanh(struct fpemu *fe)
{
- /* stub */
- return &fe->fe_f2;
+ struct fpn x;
+ struct fpn t;
+ struct fpn *r;
+
+ if (ISNAN(&fe->fe_f2))
+ return &fe->fe_f2;
+ if (ISINF(&fe->fe_f2))
+ return fpu_newnan(fe);
+
+ /*
+ * if x is +0/-0, 68000PRM.pdf says it returns +0/-0 but
+ * my real 68882 returns +0 for both.
+ */
+ if (ISZERO(&fe->fe_f2)) {
+ fe->fe_f2.fp_sign = 0;
+ return &fe->fe_f2;
+ }
+
+ /*
+ * -INF if x == -1
+ * +INF if x == 1
+ */
+ r = &fe->fe_f2;
+ if (r->fp_exp == 0 && r->fp_mant[0] == FP_1 &&
+ r->fp_mant[1] == 0 && r->fp_mant[2] == 0) {
+ r->fp_class = FPC_INF;
+ return r;
+ }
+
+ /* NAN if |x| > 1 */
+ if (fe->fe_f2.fp_exp >= 0)
+ return fpu_newnan(fe);
+
+ CPYFPN(&x, &fe->fe_f2);
+
+ /* t := 1 - x */
+ fpu_const(&fe->fe_f1, FPU_CONST_1);
+ fe->fe_f2.fp_sign = !fe->fe_f2.fp_sign;
+ r = fpu_add(fe);
+ CPYFPN(&t, r);
+
+ /* r := 1 + x */
+ fpu_const(&fe->fe_f1, FPU_CONST_1);
+ CPYFPN(&fe->fe_f2, &x);
+ r = fpu_add(fe);
+
+ /* (1-x)/(1+x) */
+ CPYFPN(&fe->fe_f1, r);
+ CPYFPN(&fe->fe_f2, &t);
+ r = fpu_div(fe);
+
+ /* log((1-x)/(1+x)) */
+ CPYFPN(&fe->fe_f2, r);
+ r = fpu_logn(fe);
+
+ /* r /= 2 */
+ r->fp_exp--;
+
+ return r;
}
/*
