1 #include <stdlib.h>
2 #include <stdio.h>
3 #include <string.h>
4
5 #include "../compiler/compiler.h"
6 #include "num2str.h"
7
8 #define ARRAY_SIZE(x) (sizeof((x)) / (sizeof((x)[0])))
9
10 /**
11 * num2str() - Cheesy number->string conversion, complete with carry rounding error.
12 * @num: quantity (e.g., number of blocks, bytes or bits)
13 * @maxlen: max number of digits in the output string (not counting prefix and units, but counting .)
14 * @base: multiplier for num (e.g., if num represents Ki, use 1024)
15 * @pow2: select unit prefix - 0=power-of-10 decimal SI, nonzero=power-of-2 binary IEC
16 * @units: select units - N2S_* macros defined in num2str.h
17 * @returns a malloc'd buffer containing "number[<unit prefix>][<units>]"
18 */
num2str(uint64_t num,int maxlen,int base,int pow2,int units)19 char *num2str(uint64_t num, int maxlen, int base, int pow2, int units)
20 {
21 const char *sistr[] = { "", "k", "M", "G", "T", "P" };
22 const char *iecstr[] = { "", "Ki", "Mi", "Gi", "Ti", "Pi" };
23 const char **unitprefix;
24 const char *unitstr[] = { "", "/s", "B", "bit", "B/s", "bit/s" };
25 const unsigned int thousand[] = { 1000, 1024 };
26 unsigned int modulo;
27 int unit_index = 0, post_index, carry = 0;
28 char tmp[32], fmt[32];
29 char *buf;
30
31 compiletime_assert(sizeof(sistr) == sizeof(iecstr), "unit prefix arrays must be identical sizes");
32
33 buf = malloc(128);
34 if (!buf)
35 return NULL;
36
37 if (pow2)
38 unitprefix = iecstr;
39 else
40 unitprefix = sistr;
41
42 for (post_index = 0; base > 1; post_index++)
43 base /= thousand[!!pow2];
44
45 switch (units) {
46 case N2S_PERSEC:
47 unit_index = 1;
48 break;
49 case N2S_BYTE:
50 unit_index = 2;
51 break;
52 case N2S_BIT:
53 unit_index = 3;
54 num *= 8;
55 break;
56 case N2S_BYTEPERSEC:
57 unit_index = 4;
58 break;
59 case N2S_BITPERSEC:
60 unit_index = 5;
61 num *= 8;
62 break;
63 }
64
65 /*
66 * Divide by K/Ki until string length of num <= maxlen.
67 */
68 modulo = -1U;
69 while (post_index < sizeof(sistr)) {
70 sprintf(tmp, "%llu", (unsigned long long) num);
71 if (strlen(tmp) <= maxlen)
72 break;
73
74 modulo = num % thousand[!!pow2];
75 num /= thousand[!!pow2];
76 carry = modulo >= thousand[!!pow2] / 2;
77 post_index++;
78 }
79
80 /*
81 * If no modulo, then we're done.
82 */
83 if (modulo == -1U) {
84 done:
85 if (post_index >= ARRAY_SIZE(sistr))
86 post_index = 0;
87
88 sprintf(buf, "%llu%s%s", (unsigned long long) num,
89 unitprefix[post_index], unitstr[unit_index]);
90 return buf;
91 }
92
93 /*
94 * If no room for decimals, then we're done.
95 */
96 sprintf(tmp, "%llu", (unsigned long long) num);
97 if ((int)(maxlen - strlen(tmp)) <= 1) {
98 if (carry)
99 num++;
100 goto done;
101 }
102
103 /*
104 * Fill in everything and return the result.
105 */
106 assert(maxlen - strlen(tmp) - 1 > 0);
107 assert(modulo < thousand[!!pow2]);
108 sprintf(fmt, "%%.%df", (int)(maxlen - strlen(tmp) - 1));
109 sprintf(tmp, fmt, (double)modulo / (double)thousand[!!pow2]);
110
111 sprintf(buf, "%llu.%s%s%s", (unsigned long long) num, &tmp[2],
112 unitprefix[post_index], unitstr[unit_index]);
113 return buf;
114 }
115