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authorRoland McGrath <roland@gnu.org>1996-03-14 11:20:03 +0000
committerRoland McGrath <roland@gnu.org>1996-03-14 11:20:03 +0000
commit52e9a9d1187e1a2a7357f3a0f353058e14667d62 (patch)
treed898bcf42f7d0a756d27f8386c093f338699a6c8 /stdlib/erand48_r.c
parent6c46dada59a56f8748f6d956ef5d318155195840 (diff)
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Thu Mar 14 06:01:07 1996 Roland McGrath <roland@charlie-brown.gnu.ai.mit.edu>
* string/strnlen.c: New file. * string/Makefile (routines): Add strnlen. * string/string.h [__USE_GNU] (strnlen): Declare new function. [__OPTIMIZE__]: Define extern inline implementation of it. * stdlib/erand48_r.c: Use __mpn_construct_double instead of ldexp and addition, to avoid using anything from -lm. Mon Mar 4 21:57:14 1996 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de> * sysdeps/unix/sysv/linux/m68k/Makefile: New file. * sysdeps/unix/sysv/linux/m68k/sysdep.h (SYS_ify): Redefine. (CALL_MCOUNT): New macro, empty unless [PROF]. (ENTRY): Do CALL_MCOUNT just after the label. (JUMPTARGET): New macro. (SYSCALL_ERROR_HANDLER): Fix syntax. Thu Mar 14 04:20:48 1996 Roland McGrath <roland@charlie-brown.gnu.ai.mit.edu> * sysdeps/unix/sysv/linux/init-first.c (init): Call `__personality' function instead of using inline asm i386 syscall. * sysdeps/unix/sysv/linux/syscalls.list: Add personality syscall. * posix/unistd.h [__USE_BSD]: Declare usleep. * misc/efgcvt.c (MAXDIG): New macro computed from <floats.h> constants. (fcvt, ecvt): Use it for buffer size. * stdlib/drand48-iter.c (__drand48_iterate): Use u_int64_t instead of conditionalizing long vs long long. * stdlib/drand48-iter.c (__drand48_iterate): Don't check for null pointers; never return EFAULT. * stdlib/drand48_r.c (drand48_r): Likewise. * stdlib/erand48_r.c (erand48_r): Likewise.
Diffstat (limited to 'stdlib/erand48_r.c')
-rw-r--r--stdlib/erand48_r.c42
1 files changed, 26 insertions, 16 deletions
diff --git a/stdlib/erand48_r.c b/stdlib/erand48_r.c
index 86d2f73..ab41474 100644
--- a/stdlib/erand48_r.c
+++ b/stdlib/erand48_r.c
@@ -17,9 +17,15 @@ License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
-#include <errno.h>
-#include <math.h>
#include <stdlib.h>
+#include "gmp.h"
+#include "gmp-mparam.h"
+#include <float.h>
+
+
+/* Function to construct a floating point number from an MP integer
+ containing the fraction bits, a base 2 exponent, and a sign flag. */
+extern double __mpn_construct_double (mp_srcptr mpn, int exponent, int neg);
int
erand48_r (xsubi, buffer, result)
@@ -27,26 +33,30 @@ erand48_r (xsubi, buffer, result)
struct drand48_data *buffer;
double *result;
{
- int i;
-
- /* Be generous for the arguments, detect some errors. */
- if (result == NULL)
- {
- errno = EFAULT;
- return -1;
- }
+ mp_limb mpn[(3 * sizeof (unsigned short int) + sizeof (mp_limb) - 1)
+ / sizeof (mp_limb)];
/* Compute next state. */
if (__drand48_iterate (xsubi, buffer) < 0)
return -1;
- *result = 0.0;
- for (i = 4 / sizeof (unsigned short int); i >= 0; --i)
- {
- double factor = ldexp (1.0, (i - 6) * sizeof (unsigned short int));
+ /* Build a 48-bit mpn containing the 48 random bits. */
+
+#if BITS_PER_MP_LIMB == 64
+ mpn[0] = (xsubi[0] << 32) | (xsubi[1] << 16) | xsubi[2];
+#elif BITS_PER_MP_LIMB == 32
+ mpn[0] = (xsubi[1] << 16) | xsubi[2];
+ mpn[1] = xsubi[0];
+#else
+ #error "BITS_PER_MP_LIMB value not handled"
+#endif
+
+ /* Shift them up so they are most significant bits of the fraction. */
+ __mpn_lshift (mpn, mpn, sizeof mpn / sizeof mpn[0], DBL_MANT_DIG - 48);
- *result += factor * (double) xsubi[i];
- }
+ /* Construct a positive double using those bits for the fractional part,
+ and a zero exponent so the resulting FP number is [0.0,1.0). */
+ *result = __mpn_construct_double (mpn, 0, 0);
return 0;
}