lib/sh/uconvert.c

   1 /* uconvert - convert string representations of decimal numbers into whole
   2               number/fractional value pairs. */
   3
   4 /* Copyright (C) 2008,2009,2020 Free Software Foundation, Inc.
   5
   6    This file is part of GNU Bush, the Bourne Again SHell.
   7
   8    Bush is free software: you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation, either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    Bush is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with Bush.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "config.h"
  23
  24 #include "bushtypes.h"
  25
  26 #include "posixtime.h"
  27
  28 #if defined (HAVE_UNISTD_H)
  29 #include <unistd.h>
  30 #endif
  31
  32 #include <stdio.h>
  33 #include "chartypes.h"
  34
  35 #include "shell.h"
  36 #include "builtins.h"
  37
  38 #define DECIMAL '.'             /* XXX - should use locale */
  39
  40 #define RETURN(x) \
  41 do { \
  42   if (ip) *ip = ipart * mult; \
  43   if (up) *up = upart; \
  44   if (ep) *ep = p; \
  45   return (x); \
  46 } while (0)
  47
  48 /*
  49  * An incredibly simplistic floating point converter.
  50  */
  51 static int multiplier[7] = { 1, 100000, 10000, 1000, 100, 10, 1 };
  52
  53 /* Take a decimal number int-part[.[micro-part]] and convert it to the whole
  54    and fractional portions.  The fractional portion is returned in
  55    millionths (micro); callers are responsible for multiplying appropriately.
  56    EP, if non-null, gets the address of the character where conversion stops.
  57    Return 1 if value converted; 0 if invalid integer for either whole or
  58    fractional parts. */
  59 int
  60 uconvert(s, ip, up, ep)
  61      char *s;
  62      long *ip, *up;
  63      char **ep;
  64 {
  65   int n, mult;
  66   long ipart, upart;
  67   char *p;
  68
  69   ipart = upart = 0;
  70   mult = 1;
  71
  72   if (s && (*s == '-' || *s == '+'))
  73     {
  74       mult = (*s == '-') ? -1 : 1;
  75       p = s + 1;
  76     }
  77   else
  78     p = s;
  79
  80   for ( ; p && *p; p++)
  81     {
  82       if (*p == DECIMAL)                /* decimal point */
  83         break;
  84       if (DIGIT(*p) == 0)
  85         RETURN(0);
  86       ipart = (ipart * 10) + (*p - '0');
  87     }
  88
  89   if (p == 0 || *p == 0)        /* callers ensure p can never be 0; this is to shut up clang */
  90     RETURN(1);
  91
  92   if (*p == DECIMAL)
  93     p++;
  94
  95   /* Look for up to six digits past a decimal point. */
  96   for (n = 0; n < 6 && p[n]; n++)
  97     {
  98       if (DIGIT(p[n]) == 0)
  99         {
 100           if (ep)
 101             {
 102               upart *= multiplier[n];
 103               p += n;           /* To set EP */
 104             }
 105           RETURN(0);
 106         }
 107       upart = (upart * 10) + (p[n] - '0');
 108     }
 109
 110   /* Now convert to millionths */
 111   upart *= multiplier[n];
 112
 113   if (n == 6 && p[6] >= '5' && p[6] <= '9')
 114     upart++;                    /* round up 1 */
 115
 116   if (ep)
 117     {
 118       p += n;
 119       while (DIGIT(*p))
 120         p++;
 121     }
 122
 123   RETURN(1);
 124 }