diff options
Diffstat (limited to 'stdlib/drand48-iter.c')
| -rw-r--r-- | stdlib/drand48-iter.c | 57 |
1 files changed, 19 insertions, 38 deletions
diff --git a/stdlib/drand48-iter.c b/stdlib/drand48-iter.c index 967c404706..65e78eb3ce 100644 --- a/stdlib/drand48-iter.c +++ b/stdlib/drand48-iter.c @@ -20,7 +20,7 @@ Boston, MA 02111-1307, USA. */ #include <errno.h> #include <stdlib.h> #include <limits.h> - +#include <sys/types.h> /* Global state for non-reentrent functions. */ struct drand48_data __libc_drand48_data; @@ -31,12 +31,7 @@ __drand48_iterate (xsubi, buffer) unsigned short int xsubi[3]; struct drand48_data *buffer; { - /* Be generous for the arguments, detect some errors. */ - if (xsubi == NULL || buffer == NULL) - { - errno = EFAULT; - return -1; - } + u_int64_t X, a, result; /* Initialize buffer, if not yet done. */ if (!buffer->init) @@ -58,42 +53,28 @@ __drand48_iterate (xsubi, buffer) 48 bits. Because we compute the modulus it does not care how many bits really are computed. */ - if (sizeof (long int) >= 6) + if (sizeof (unsigned short int) == 2) { - /* The `long' data type is sufficent. */ - unsigned long int X, a, result; + X = (xsubi[2] << 16 | xsubi[1]) << 16 | xsubi[0]; + a = (buffer->a[2] << 16 | buffer->a[1]) << 16 | buffer->a[0]; -#define ONE_STEP \ - if (sizeof (unsigned short int) == 2) \ - { \ - X = (xsubi[2] << 16 | xsubi[1]) << 16 | xsubi[0]; \ - a = (buffer->a[2] << 16 | buffer->a[1]) << 16 | buffer->a[0]; \ - \ - result = X * a + buffer->c; \ - \ - xsubi[0] = result & 0xffff; \ - result >>= 16; \ - xsubi[1] = result & 0xffff; \ - result >>= 16; \ - xsubi[2] = result & 0xffff; \ - } \ - else \ - { \ - X = xsubi[2] << 16 | xsubi[1] >> 16; \ - a = buffer->a[2] << 16 | buffer->a[1] >> 16; \ - \ - result = X * a + buffer->c; \ - \ - xsubi[0] = result >> 16 & 0xffffffffl; \ - xsubi[1] = result << 16 & 0xffff0000l; \ - } - ONE_STEP; + result = X * a + buffer->c; + + xsubi[0] = result & 0xffff; + result >>= 16; + xsubi[1] = result & 0xffff; + result >>= 16; + xsubi[2] = result & 0xffff; } else { - /* We have to use the `long long' data type. */ - unsigned long long int X, a, result; - ONE_STEP; + X = xsubi[2] << 16 | xsubi[1] >> 16; + a = buffer->a[2] << 16 | buffer->a[1] >> 16; + + result = X * a + buffer->c; + + xsubi[0] = result >> 16 & 0xffffffffl; + xsubi[1] = result << 16 & 0xffff0000l; } return 0; |