1 /*
2 * Copyright (C) 2018-2022 Intel Corporation.
3 *
4 * SPDX-License-Identifier: BSD-3-Clause
5 */
6
7 #include <types.h>
8 #include <rtl.h>
9
10 /*
11 * Convert a string to a long integer - decimal support only.
12 */
strtol_deci(const char * nptr)13 int64_t strtol_deci(const char *nptr)
14 {
15 const char *s = nptr;
16 char c;
17 uint64_t acc, cutoff, cutlim;
18 int32_t neg = 0, any;
19 uint64_t base = 10UL;
20
21 /*
22 * Skip white space and pick up leading +/- sign if any.
23 */
24 do {
25 c = *s;
26 s++;
27 } while (is_space(c));
28
29 if (c == '-') {
30 neg = 1;
31 c = *s;
32 s++;
33 } else if (c == '+') {
34 c = *s;
35 s++;
36 } else {
37 /* No sign character. */
38 }
39
40 /*
41 * Compute the cutoff value between legal numbers and illegal
42 * numbers. That is the largest legal value, divided by the
43 * base. An input number that is greater than this value, if
44 * followed by a legal input character, is too big. One that
45 * is equal to this value may be valid or not; the limit
46 * between valid and invalid numbers is then based on the last
47 * digit. For instance, if the range for longs is
48 * [-2147483648..2147483647] and the input base is 10,
49 * cutoff will be set to 214748364 and cutlim to either
50 * 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
51 * a value > 214748364, or equal but the next digit is > 7 (or 8),
52 * the number is too big, and we will return a range error.
53 *
54 * Set any if any `digits' consumed; make it negative to indicate
55 * overflow.
56 */
57 cutoff = (neg != 0) ? LONG_MIN : LONG_MAX;
58 cutlim = cutoff % base;
59 cutoff /= base;
60 acc = 0UL;
61 any = 0;
62
63 while ((c >= '0') && (c <= '9')) {
64 c -= '0';
65 if ((acc > cutoff) ||
66 ((acc == cutoff) && ((uint64_t)c > cutlim))) {
67 any = -1;
68 break;
69 } else {
70 acc *= base;
71 acc += (uint64_t)c;
72 }
73
74 c = *s;
75 s++;
76 }
77
78 if (any < 0) {
79 acc = (neg != 0) ? LONG_MIN : LONG_MAX;
80 } else if (neg != 0) {
81 acc = ~acc + 1UL;
82 } else {
83 /* There is no overflow and no leading '-' exists. In such case
84 * acc already holds the right number. No action required. */
85 }
86 return (long)acc;
87 }
88