pal: Handle a missing copysign() function

Some older compilers are missing copysign() and we can't simply
replace it with the dsign() macro from SOFA. The main issue is
that strtod() can return -0.0 and copysign can correctly note
that. When copysign() is missing we have to go back to scanning
the string for minus signs.

component.xml

@@ -3,7 +3,7 @@
 <!-- component.xml.  Generated from component.xml.in by configure. -->
 
 <component id="pal" support="S">
-  <version>0.1.1</version>
+  <version>0.1.2</version>
   <path>libraries/pal</path>
   <description>Position Astronomy Library</description>
   <abstract><p>

configure.ac

@@ -2,7 +2,7 @@ dnl    Process this file with autoconf to produce a configure script
 AC_REVISION($Revision: 27534 $)
 
 dnl    Initialisation: package name and version number
-AC_INIT(pal, 0.1.1, [email protected])
+AC_INIT(pal, 0.1.2, [email protected])
 
 dnl    Require autoconf-2.50 at least
 AC_PREREQ(2.50)
@@ -23,6 +23,8 @@ AC_PROG_LIBTOOL
 #   If --with-pic=no is set we should honour that.
 AM_CONDITIONAL(NOPIC, test x$pic_mode = xno)
 
+dnl    copysign is a c99 feature
+AC_CHECK_FUNCS(copysign)
 
 dnl    Declare the build and use dependencies for this package
 STAR_DECLARE_DEPENDENCIES(build, [sofa starutil])

palDfltin.c

@@ -52,9 +52,16 @@
 *     - Unlike slaDfltin a standalone "E" will return status 1 (could not find
 *       a number) rather than 2 (bad number).
 
+*  Implementation Status:
+*     - The code is more robust if the C99 copysign() function is available.
+*     This can recognize the -0.0 values returned by strtod. If copysign() is
+*     missing we try to scan the string looking for minus signs.
+
 *  History:
 *     2012-03-08 (TIMJ):
 *        Initial version based on strtod
+*     2012-06-21 (TIMJ):
+*        Provide a backup for missing copysign.
 *     {enter_further_changes_here}
 
 *  Copyright:
@@ -82,6 +89,10 @@
 *-
 */
 
+#if HAVE_CONFIG_H
+#include <config.h>
+#endif
+
 /* Shenanigans for isblank() which is C99 only */
 #define _POSIX_C_SOURCE 200112L
 #define _ISOC99_SOURCE
@@ -93,6 +104,12 @@
 
 #include "pal.h"
 
+#if HAVE_COPYSIGN
+# define SCAN_FOR_MINUS 0
+#else
+# define SCAN_FOR_MINUS 1
+#endif
+
 /* We prefer to use the starutil package */
 #if NOSTARUTIL
 #else
@@ -112,6 +129,28 @@ void palDfltin( const char * string, int *nstrt,
      D or d in the string. */
   char tempbuf[256];
 
+#if SCAN_FOR_MINUS
+  int dreslt_sign = 1;
+  int ipos = *nstrt;
+  const char * cctemp = NULL;
+
+  /* Scan the string looking for a minus sign. Then update the
+     start position for the subsequent copy iff we find a '-'.
+     Note  that commas are a special delimiter so we stop looking for a
+     minus if we find one or if we find a digit. */
+  cctemp = &(string[ipos-1]);
+  while (!isdigit(*cctemp) && (*cctemp != ',') && (*cctemp != '\0')) {
+    printf("Looking at char %d '%c'\n",ipos-1, *cctemp);
+    if (*cctemp == '-') {
+      *nstrt = ipos;
+      dreslt_sign = -1;
+      break;
+    }
+    ipos++;
+    cctemp++;
+  }
+#endif
+
   /* Correct for SLA use of fortran convention */
 #if NOSTARUTIL
   /* Use standard C interface */
@@ -149,6 +188,9 @@ void palDfltin( const char * string, int *nstrt,
   } else if ( errno == ERANGE ) {
     *jflag = 2;
   } else {
+#if SCAN_FOR_MINUS
+    *jflag = (dreslt_sign < 0 ? -1 : 0);
+#else
     if ( retval < 0.0 ) {
       *jflag = -1;
     } else if ( retval == 0.0 ) {
@@ -162,6 +204,7 @@ void palDfltin( const char * string, int *nstrt,
     } else {
       *jflag = 0;
     }
+#endif
   }
 
   /* Sort out the position for the next index */

palPertue.c

@@ -151,6 +151,8 @@
 *  History:
 *     2012-03-12 (TIMJ):
 *        Initial version direct conversion of SLA/F.
+*     2012-06-21 (TIMJ):
+*        Support a lack of copysign() function.
 *     {enter_further_changes_here}
 
 *  Copyright:
@@ -178,6 +180,10 @@
 *-
 */
 
+#if HAVE_CONFIG_H
+#include <config.h>
+#endif
+
 #include <math.h>
 
 #include "pal.h"
@@ -188,6 +194,13 @@
 #define MAX(x, y) (((x) > (y)) ? (x) : (y))
 #define MIN(x, y) (((x) < (y)) ? (x) : (y))
 
+/* copysign is C99 */
+#if HAVE_COPYSIGN
+# define COPYSIGN copysign
+#else
+# define COPYSIGN(a,b) DSIGN(a,b)
+#endif
+
 void palPertue( double date, double u[13], int *jstat ) {
 
   /*  Distance from EMB at which Earth and Moon are treated separately */
@@ -344,7 +357,7 @@ void palPertue( double date, double u[13], int *jstat ) {
   if (fabs(TSPAN) > 36525.0) *jstat=101;
 
   /*  Time direction: +1 for forwards, -1 for backwards. */
-  FB = copysign(1.0,TSPAN);
+  FB = COPYSIGN(1.0,TSPAN);
 
   /*  Initialize relative epoch for start of current timestep. */
   RTN = 0.0;

palmac.h

@@ -109,5 +109,9 @@ static const double PAL__GCON = 0.01720209895;
 /* DMAX(A,B) - return maximum value - evaluates arguments multiple times */
 #define DMAX(A,B) (A > B ? A : B )
 
+/* We actually prefer to use C99 copysign() but we define this here as a backup
+   but it will not detect -0.0 so is not useful for palDfltin. */
+/* DSIGN(A,B) - magnitude of A with sign of B (double) */
+#define DSIGN(A,B) ((B)<0.0?-fabs(A):fabs(A))
 
 #endif