1 // SPDX-License-Identifier: GPL-2.0-only
2 /* -*- linux-c -*- ------------------------------------------------------- *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright 2007 rPath, Inc. - All Rights Reserved
7 * ----------------------------------------------------------------------- */
10 * Oh, it's a waste of space, but oh-so-yummy for debugging.
15 #include <linux/compiler.h>
16 #include <linux/ctype.h>
17 #include <linux/kernel.h>
18 #include <linux/limits.h>
19 #include <linux/string.h>
22 int skip_atoi(const char **s)
27 i = i * 10 + *((*s)++) - '0';
32 * put_dec_full4 handles numbers in the range 0 <= r < 10000.
33 * The multiplier 0xccd is round(2^15/10), and the approximation
34 * r/10 == (r * 0xccd) >> 15 is exact for all r < 16389.
37 void put_dec_full4(char *end, unsigned int r)
41 for (i = 0; i < 3; i++) {
42 unsigned int q = (r * 0xccd) >> 15;
43 *--end = '0' + (r - q * 10);
49 /* put_dec is copied from lib/vsprintf.c with small modifications */
52 * Call put_dec_full4 on x % 10000, return x / 10000.
53 * The approximation x/10000 == (x * 0x346DC5D7) >> 43
54 * holds for all x < 1,128,869,999. The largest value this
55 * helper will ever be asked to convert is 1,125,520,955.
56 * (second call in the put_dec code, assuming n is all-ones).
59 unsigned int put_dec_helper4(char *end, unsigned int x)
61 unsigned int q = (x * 0x346DC5D7ULL) >> 43;
63 put_dec_full4(end, x - q * 10000);
67 /* Based on code by Douglas W. Jones found at
68 * <http://www.cs.uiowa.edu/~jones/bcd/decimal.html#sixtyfour>
69 * (with permission from the author).
70 * Performs no 64-bit division and hence should be fast on 32-bit machines.
73 char *put_dec(char *end, unsigned long long n)
75 unsigned int d3, d2, d1, q, h;
78 d1 = ((unsigned int)n >> 16); /* implicit "& 0xffff" */
81 d3 = (h >> 16); /* implicit "& 0xffff" */
83 /* n = 2^48 d3 + 2^32 d2 + 2^16 d1 + d0
84 = 281_4749_7671_0656 d3 + 42_9496_7296 d2 + 6_5536 d1 + d0 */
85 q = 656 * d3 + 7296 * d2 + 5536 * d1 + ((unsigned int)n & 0xffff);
86 q = put_dec_helper4(p, q);
89 q += 7671 * d3 + 9496 * d2 + 6 * d1;
90 q = put_dec_helper4(p, q);
93 q += 4749 * d3 + 42 * d2;
94 q = put_dec_helper4(p, q);
98 q = put_dec_helper4(p, q);
104 /* strip off the extra 0's we printed */
105 while (p < end && *p == '0')
112 char *number(char *end, unsigned long long num, int base, char locase)
115 * locase = 0 or 0x20. ORing digits or letters with 'locase'
116 * produces same digits or (maybe lowercased) letters
119 /* we are called with base 8, 10 or 16, only, thus don't need "G..." */
120 static const char digits[16] = "0123456789ABCDEF"; /* "GHIJKLMNOPQRSTUVWXYZ"; */
125 end = put_dec(end, num);
128 for (; num != 0; num >>= 3)
129 *--end = '0' + (num & 07);
132 for (; num != 0; num >>= 4)
133 *--end = digits[num & 0xf] | locase;
142 #define ZEROPAD 1 /* pad with zero */
143 #define SIGN 2 /* unsigned/signed long */
144 #define PLUS 4 /* show plus */
145 #define SPACE 8 /* space if plus */
146 #define LEFT 16 /* left justified */
147 #define SMALL 32 /* Must be 32 == 0x20 */
148 #define SPECIAL 64 /* 0x */
151 int get_flags(const char **fmt)
180 int get_int(const char **fmt, va_list *ap)
183 return skip_atoi(fmt);
186 /* it's the next argument */
187 return va_arg(*ap, int);
193 unsigned long long get_number(int sign, int qualifier, va_list *ap)
198 return va_arg(*ap, long long);
200 return va_arg(*ap, long);
202 return (short)va_arg(*ap, int);
204 return (signed char)va_arg(*ap, int);
206 return va_arg(*ap, int);
211 return va_arg(*ap, unsigned long long);
213 return va_arg(*ap, unsigned long);
215 return (unsigned short)va_arg(*ap, int);
217 return (unsigned char)va_arg(*ap, int);
219 return va_arg(*ap, unsigned int);
225 char get_sign(long long *num, int flags)
240 int vsprintf(char *buf, const char *fmt, va_list ap)
242 /* The maximum space required is to print a 64-bit number in octal */
243 char tmp[(sizeof(unsigned long long) * 8 + 2) / 3];
244 char *tmp_end = &tmp[ARRAY_SIZE(tmp)];
252 int flags; /* flags to number() */
254 int field_width; /* width of output field */
255 int precision; /* min. # of digits for integers; max
256 number of chars for from string */
257 int qualifier; /* 'h', 'hh', 'l' or 'll' for integer fields */
262 * We want to pass our input va_list to helper functions by reference,
263 * but there's an annoying edge case. If va_list was originally passed
264 * to us by value, we could just pass &ap down to the helpers. This is
265 * the case on, for example, X86_32.
266 * However, on X86_64 (and possibly others), va_list is actually a
267 * size-1 array containing a structure. Our function parameter ap has
268 * decayed from T[1] to T*, and &ap has type T** rather than T(*)[1],
269 * which is what will be expected by a function taking a va_list *
271 * One standard way to solve this mess is by creating a copy in a local
272 * variable of type va_list and then passing a pointer to that local
273 * copy instead, which is what we do here.
277 for (str = buf; *fmt; ++fmt) {
278 if (*fmt != '%' || *++fmt == '%') {
284 flags = get_flags(&fmt);
286 /* get field width */
287 field_width = get_int(&fmt, &args);
288 if (field_width < 0) {
289 field_width = -field_width;
296 /* get the precision */
300 precision = get_int(&fmt, &args);
305 /* get the conversion qualifier */
307 if (*fmt == 'h' || *fmt == 'l') {
310 if (qualifier == *fmt) {
311 qualifier -= 'a'-'A';
321 tmp[0] = (unsigned char)va_arg(args, int);
330 s = va_arg(args, char *);
332 s = precision < 6 ? "" : "(null)";
333 precision = len = strnlen(s, precision);
336 /* integer number formats - set up the flags and "break" */
343 precision = 2 * sizeof(void *);
363 * Bail out if the conversion specifier is invalid.
364 * There's probably a typo in the format string and the
365 * remaining specifiers are unlikely to match up with
371 num = (unsigned long)va_arg(args, void *);
373 num = get_number(flags & SIGN, qualifier, &args);
376 sign = get_sign(&num, flags);
380 s = number(tmp_end, num, base, flags & SMALL);
382 /* default precision is 1 */
385 /* precision is minimum number of digits to print */
388 if (flags & SPECIAL) {
390 * For octal, a leading 0 is printed only if necessary,
391 * i.e. if it's not already there because of the
394 if (base == 8 && precision == len)
397 * For hexadecimal, the leading 0x is skipped if the
398 * output is empty, i.e. both the number and the
401 if (base == 16 && precision > 0)
407 * For zero padding, increase the precision to fill the field
410 if ((flags & ZEROPAD) && field_width > precision)
411 precision = field_width;
414 /* Calculate the padding necessary */
415 field_width -= precision;
416 /* Leading padding with ' ' */
418 while (field_width-- > 0)
423 /* 0x/0X for hexadecimal */
424 if (flags & SPECIAL) {
426 *str++ = 'X' | (flags & SMALL);
428 /* Zero padding and excess precision */
429 while (precision-- > len)
434 /* Trailing padding with ' ' */
435 while (field_width-- > 0)
446 int sprintf(char *buf, const char *fmt, ...)
452 i = vsprintf(buf, fmt, args);