1 /*
2 * strtoul.c --
3 *
4 * Source code for the "strtoul" library procedure.
5 *
6 * Copyright 1988 Regents of the University of California
7 * Permission to use, copy, modify, and distribute this
8 * software and its documentation for any purpose and without
9 * fee is hereby granted, provided that the above copyright
10 * notice appear in all copies. The University of California
11 * makes no representations about the suitability of this
12 * software for any purpose. It is provided "as is" without
13 * express or implied warranty.
14 */
15
16 #include <ctype.h>
17
18 /*
19 * The table below is used to convert from ASCII digits to a
20 * numerical equivalent. It maps from '0' through 'z' to integers
21 * (100 for non-digit characters).
22 */
23
24 static char cvtIn[] = {
25 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, /* '0' - '9' */
26 100, 100, 100, 100, 100, 100, 100, /* punctuation */
27 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, /* 'A' - 'Z' */
28 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
29 30, 31, 32, 33, 34, 35,
30 100, 100, 100, 100, 100, 100, /* punctuation */
31 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, /* 'a' - 'z' */
32 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
33 30, 31, 32, 33, 34, 35};
34
35 /*
36 *----------------------------------------------------------------------
37 *
38 * strtoul --
39 *
40 * Convert an ASCII string into an integer.
41 *
42 * Results:
43 * The return value is the integer equivalent of string. If endPtr
44 * is non-NULL, then *endPtr is filled in with the character
45 * after the last one that was part of the integer. If string
46 * doesn't contain a valid integer value, then zero is returned
47 * and *endPtr is set to string.
48 *
49 * Side effects:
50 * None.
51 *
52 *----------------------------------------------------------------------
53 */
54
55 unsigned long int
56 strtoul(string, endPtr, base)
57 char *string; /* String of ASCII digits, possibly
58 * preceded by white space. For bases
59 * greater than 10, either lower- or
60 * upper-case digits may be used.
61 */
62 char **endPtr; /* Where to store address of terminating
63 * character, or NULL. */
64 int base; /* Base for conversion. Must be less
65 * than 37. If 0, then the base is chosen
66 * from the leading characters of string:
67 * "0x" means hex, "0" means octal, anything
68 * else means decimal.
69 */
70 {
71 register char *p;
72 register unsigned long int result = 0;
73 register unsigned digit;
74 int anyDigits = 0;
75
76 /*
77 * Skip any leading blanks.
78 */
79
80 p = string;
81 while (isspace(*p)) {
82 p += 1;
83 }
84
85 /*
86 * If no base was provided, pick one from the leading characters
87 * of the string.
88 */
89
90 if (base == 0)
91 {
92 if (*p == '0') {
93 p += 1;
94 if (*p == 'x') {
95 p += 1;
96 base = 16;
97 } else {
98
99 /*
100 * Must set anyDigits here, otherwise "0" produces a
101 * "no digits" error.
102 */
103
104 anyDigits = 1;
105 base = 8;
106 }
107 }
108 else base = 10;
109 } else if (base == 16) {
110
111 /*
112 * Skip a leading "0x" from hex numbers.
113 */
114
115 if ((p[0] == '0') && (p[1] == 'x')) {
116 p += 2;
117 }
118 }
119
120 /*
121 * Sorry this code is so messy, but speed seems important. Do
122 * different things for base 8, 10, 16, and other.
123 */
124
125 if (base == 8) {
126 for ( ; ; p += 1) {
127 digit = *p - '0';
128 if (digit > 7) {
129 break;
130 }
131 result = (result << 3) + digit;
132 anyDigits = 1;
133 }
134 } else if (base == 10) {
135 for ( ; ; p += 1) {
136 digit = *p - '0';
137 if (digit > 9) {
138 break;
139 }
140 result = (10*result) + digit;
141 anyDigits = 1;
142 }
143 } else if (base == 16) {
144 for ( ; ; p += 1) {
145 digit = *p - '0';
146 if (digit > ('z' - '0')) {
147 break;
148 }
149 digit = cvtIn[digit];
150 if (digit > 15) {
151 break;
152 }
153 result = (result << 4) + digit;
154 anyDigits = 1;
155 }
156 } else {
157 for ( ; ; p += 1) {
158 digit = *p - '0';
159 if (digit > ('z' - '0')) {
160 break;
161 }
162 digit = cvtIn[digit];
163 if (digit >= base) {
164 break;
165 }
166 result = result*base + digit;
167 anyDigits = 1;
168 }
169 }
170
171 /*
172 * See if there were any digits at all.
173 */
174
175 if (!anyDigits) {
176 p = string;
177 }
178
179 if (endPtr != 0) {
180 *endPtr = p;
181 }
182
183 return result;
184 }