MySQL 5.6.14 Source Code Document
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int2str.c
1 /* Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
2 
3  This program is free software; you can redistribute it and/or modify
4  it under the terms of the GNU General Public License as published by
5  the Free Software Foundation; version 2 of the License.
6 
7  This program is distributed in the hope that it will be useful,
8  but WITHOUT ANY WARRANTY; without even the implied warranty of
9  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10  GNU General Public License for more details.
11 
12  You should have received a copy of the GNU General Public License
13  along with this program; if not, write to the Free Software
14  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
15 
16 #include <my_global.h>
17 #include "m_string.h"
18 
19 /*
20  _dig_vec arrays are public because they are used in several outer places.
21 */
22 char _dig_vec_upper[] =
23  "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
24 char _dig_vec_lower[] =
25  "0123456789abcdefghijklmnopqrstuvwxyz";
26 
27 
28 /*
29  Convert integer to its string representation in given scale of notation.
30 
31  SYNOPSIS
32  int2str()
33  val - value to convert
34  dst - points to buffer where string representation should be stored
35  radix - radix of scale of notation
36  upcase - set to 1 if we should use upper-case digits
37 
38  DESCRIPTION
39  Converts the (long) integer value to its character form and moves it to
40  the destination buffer followed by a terminating NUL.
41  If radix is -2..-36, val is taken to be SIGNED, if radix is 2..36, val is
42  taken to be UNSIGNED. That is, val is signed if and only if radix is.
43  All other radixes treated as bad and nothing will be changed in this case.
44 
45  For conversion to decimal representation (radix is -10 or 10) one can use
46  optimized int10_to_str() function.
47 
48  RETURN VALUE
49  Pointer to ending NUL character or NullS if radix is bad.
50 */
51 
52 char *
53 int2str(register long int val, register char *dst, register int radix,
54  int upcase)
55 {
56  char buffer[65];
57  register char *p;
58  long int new_val;
59  char *dig_vec= upcase ? _dig_vec_upper : _dig_vec_lower;
60  ulong uval= (ulong) val;
61 
62  if (radix < 0)
63  {
64  if (radix < -36 || radix > -2)
65  return NullS;
66  if (val < 0)
67  {
68  *dst++ = '-';
69  /* Avoid integer overflow in (-val) for LONGLONG_MIN (BUG#31799). */
70  uval = (ulong)0 - uval;
71  }
72  radix = -radix;
73  }
74  else if (radix > 36 || radix < 2)
75  return NullS;
76 
77  /*
78  The slightly contorted code which follows is due to the fact that
79  few machines directly support unsigned long / and %. Certainly
80  the VAX C compiler generates a subroutine call. In the interests
81  of efficiency (hollow laugh) I let this happen for the first digit
82  only; after that "val" will be in range so that signed integer
83  division will do. Sorry 'bout that. CHECK THE CODE PRODUCED BY
84  YOUR C COMPILER. The first % and / should be unsigned, the second
85  % and / signed, but C compilers tend to be extraordinarily
86  sensitive to minor details of style. This works on a VAX, that's
87  all I claim for it.
88  */
89  p = &buffer[sizeof(buffer)-1];
90  *p = '\0';
91  new_val= uval / (ulong) radix;
92  *--p = dig_vec[(uchar) (uval- (ulong) new_val*(ulong) radix)];
93  val = new_val;
94 #ifdef HAVE_LDIV
95  while (val != 0)
96  {
97  ldiv_t res;
98  res=ldiv(val,radix);
99  *--p = dig_vec[res.rem];
100  val= res.quot;
101  }
102 #else
103  while (val != 0)
104  {
105  new_val=val/radix;
106  *--p = dig_vec[(uchar) (val-new_val*radix)];
107  val= new_val;
108  }
109 #endif
110  while ((*dst++ = *p++) != 0) ;
111  return dst-1;
112 }
113 
114 
115 /*
116  Converts integer to its string representation in decimal notation.
117 
118  SYNOPSIS
119  int10_to_str()
120  val - value to convert
121  dst - points to buffer where string representation should be stored
122  radix - flag that shows whenever val should be taken as signed or not
123 
124  DESCRIPTION
125  This is version of int2str() function which is optimized for normal case
126  of radix 10/-10. It takes only sign of radix parameter into account and
127  not its absolute value.
128 
129  RETURN VALUE
130  Pointer to ending NUL character.
131 */
132 
133 char *int10_to_str(long int val,char *dst,int radix)
134 {
135  char buffer[65];
136  register char *p;
137  long int new_val;
138  unsigned long int uval = (unsigned long int) val;
139 
140  if (radix < 0) /* -10 */
141  {
142  if (val < 0)
143  {
144  *dst++ = '-';
145  /* Avoid integer overflow in (-val) for LONGLONG_MIN (BUG#31799). */
146  uval = (unsigned long int)0 - uval;
147  }
148  }
149 
150  p = &buffer[sizeof(buffer)-1];
151  *p = '\0';
152  new_val= (long) (uval / 10);
153  *--p = '0'+ (char) (uval - (unsigned long) new_val * 10);
154  val = new_val;
155 
156  while (val != 0)
157  {
158  new_val=val/10;
159  *--p = '0' + (char) (val-new_val*10);
160  val= new_val;
161  }
162  while ((*dst++ = *p++) != 0) ;
163  return dst-1;
164 }