123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198 |
- /* ieee-utils/make_rep.c
- *
- * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 Brian Gough
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 3 of the License, or (at
- * your option) any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- */
- #include "gsl__config.h"
- #include "gsl_ieee_utils.h"
- #include "gsl_ieee-utils__endian.c"
- #include "gsl_ieee-utils__standardize.c"
- static void sprint_nybble(int i, char *s) ;
- static void sprint_byte(int i, char *s) ;
- static int determine_ieee_type (int non_zero, int exponent, int max_exponent);
- /* For the IEEE float format the bits are found from the following
- masks,
-
- sign = 0x80000000
- exponent = 0x7f800000
- mantisssa = 0x007fffff
- For the IEEE double format the masks are,
- sign = 0x8000000000000000
- exponent = 0x7ff0000000000000
- mantissa = 0x000fffffffffffff
- */
- void
- gsl_ieee_float_to_rep (const float * x, gsl_ieee_float_rep * r)
- {
- int e, non_zero;
- union {
- float f;
- struct {
- unsigned char byte[4] ;
- } ieee ;
- } u;
-
- u.f = *x ;
- if (little_endian_p())
- make_float_bigendian(&(u.f)) ;
-
- /* note that r->sign is signed, u.ieee.byte is unsigned */
- if (u.ieee.byte[3]>>7)
- {
- r->sign = 1 ;
- }
- else
- {
- r->sign = 0 ;
- }
- e = (u.ieee.byte[3] & 0x7f) << 1 | (u.ieee.byte[2] & 0x80)>>7 ;
-
- r->exponent = e - 127 ;
- sprint_byte((u.ieee.byte[2] & 0x7f) << 1,r->mantissa) ;
- sprint_byte(u.ieee.byte[1],r->mantissa + 7) ;
- sprint_byte(u.ieee.byte[0],r->mantissa + 15) ;
- r->mantissa[23] = '\0' ;
- non_zero = u.ieee.byte[0] || u.ieee.byte[1] || (u.ieee.byte[2] & 0x7f);
- r->type = determine_ieee_type (non_zero, e, 255) ;
- }
- void
- gsl_ieee_double_to_rep (const double * x, gsl_ieee_double_rep * r)
- {
- int e, non_zero;
- union
- {
- double d;
- struct {
- unsigned char byte[8];
- } ieee ;
- } u;
- u.d= *x ;
-
- if (little_endian_p())
- make_double_bigendian(&(u.d)) ;
-
- /* note that r->sign is signed, u.ieee.byte is unsigned */
- if (u.ieee.byte[7]>>7)
- {
- r->sign = 1 ;
- }
- else
- {
- r->sign = 0 ;
- }
- e =(u.ieee.byte[7] & 0x7f)<<4 ^ (u.ieee.byte[6] & 0xf0)>>4 ;
-
- r->exponent = e - 1023 ;
- sprint_nybble(u.ieee.byte[6],r->mantissa) ;
- sprint_byte(u.ieee.byte[5],r->mantissa + 4) ;
- sprint_byte(u.ieee.byte[4],r->mantissa + 12) ;
- sprint_byte(u.ieee.byte[3],r->mantissa + 20) ;
- sprint_byte(u.ieee.byte[2],r->mantissa + 28) ;
- sprint_byte(u.ieee.byte[1],r->mantissa + 36) ;
- sprint_byte(u.ieee.byte[0],r->mantissa + 44) ;
- r->mantissa[52] = '\0' ;
- non_zero = (u.ieee.byte[0] || u.ieee.byte[1] || u.ieee.byte[2]
- || u.ieee.byte[3] || u.ieee.byte[4] || u.ieee.byte[5]
- || (u.ieee.byte[6] & 0x0f)) ;
- r->type = determine_ieee_type (non_zero, e, 2047) ;
- }
- /* A table of character representations of nybbles */
- static char nybble[16][5]={ /* include space for the \0 */
- "0000", "0001", "0010", "0011",
- "0100", "0101", "0110", "0111",
- "1000", "1001", "1010", "1011",
- "1100", "1101", "1110", "1111"
- } ;
-
- static void
- sprint_nybble(int i, char *s)
- {
- char *c ;
- c=nybble[i & 0x0f ];
- *s=c[0] ; *(s+1)=c[1] ; *(s+2)=c[2] ; *(s+3)=c[3] ;
- }
- static void
- sprint_byte(int i, char *s)
- {
- char *c ;
- c=nybble[(i & 0xf0)>>4];
- *s=c[0] ; *(s+1)=c[1] ; *(s+2)=c[2] ; *(s+3)=c[3] ;
- c=nybble[i & 0x0f];
- *(s+4)=c[0] ; *(s+5)=c[1] ; *(s+6)=c[2] ; *(s+7)=c[3] ;
- }
- static int
- determine_ieee_type (int non_zero, int exponent, int max_exponent)
- {
- if (exponent == max_exponent)
- {
- if (non_zero)
- {
- return GSL_IEEE_TYPE_NAN ;
- }
- else
- {
- return GSL_IEEE_TYPE_INF ;
- }
- }
- else if (exponent == 0)
- {
- if (non_zero)
- {
- return GSL_IEEE_TYPE_DENORMAL ;
- }
- else
- {
- return GSL_IEEE_TYPE_ZERO ;
- }
- }
- else
- {
- return GSL_IEEE_TYPE_NORMAL ;
- }
- }
|