vsprintf.c

Intel PXA270的bootloader程序,在linux环境下运行的.

#include <types.h>
#include <ctype.h>
#include <stdarg.h>
#include <string.h>

extern int vsprintf(char *buf, const char *fmt, va_list args);

#define do_div(n, base)												\
			({														\
				int	__res;											\
				__res = ((unsigned long)(n)) % (unsigned) (base);	\
				(n) = ((unsigned long)(n)) / (unsigned)(base);		\
				__res;												\
			})


static int skip_atoi(const char **s){
	int i=0;

	while (isdigit(**s))
		i = i*10 + *((*s)++) - '0';
	return i;
}

#define ZEROPAD	1		// pad with zero.
#define SIGN	2		// unsigned/signed long.
#define PLUS	4		// show plus.
#define SPACE	8		// space if plus.
#define LEFT	16		// left justified.
#define SPECIAL	32		// 0x.
#define LARGE	64		// use 'ABCDEF' instead of 'abcdef'.

static char *number(char * str, long long num, int base, int size, int precision, int type){
	char c,sign,tmp[66];
	const char *digits="0123456789abcdefghijklmnopqrstuvwxyz";
	int i;

	if (type & LARGE) digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	if (type & LEFT) type &= ~ZEROPAD;
	if (base < 2 || base > 36) return 0;

	c = (type & ZEROPAD) ? '0' : ' ';
	sign = 0;
	if (type & SIGN){
		if (num < 0){
			sign = '-';
			num = -num;
			size--;
		} else if (type & PLUS){
			sign = '+';
			size--;
		} else if (type & SPACE){
			sign = ' ';
			size--;
		}
	}
	if (type & SPECIAL) {
		if (base == 16)
			size -= 2;
		else if (base == 8)
			size--;
	}
	i = 0;
	if (num == 0) tmp[i++]='0';
	else {
		while (num != 0) tmp[i++] = digits[do_div(num,base)];
	}

	
	if (i > precision) precision = i;
	size -= precision;

	if (!(type&(ZEROPAD+LEFT)))
		while(size-->0) *str++ = ' ';

	if (sign) *str++ = sign;

	if (type & SPECIAL) {
		if (base==8)
			*str++ = '0';
		else if (base==16) {
			*str++ = '0';
			*str++ = digits[33];
		}
	}
	if (!(type & LEFT))
		while (size-- > 0)
			*str++ = c;
	while (i < precision--)
		*str++ = '0';
	while (i-- > 0)
		*str++ = tmp[i];
	while (size-- > 0)
		*str++ = ' ';
	return str;
}

/**
 * vsprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * Call this function if you are already dealing with a va_list.
 * You probably want sprintf instead.
 */
extern int vsprintf(char *buf, const char *fmt, va_list args){
	int len;
	unsigned long long num;
	int i, base;
	char *str;
	const char *s;

	int flags;			// flags to number().
	int field_width;	// width of output field.
	int precision;		// min. # of digits for integers; max number of chars for from string.
	int qualifier;		// 'h', 'l', or 'L' for integer fields.
						// 'z' support added 23/7/1999 S.H.
						// 'z' changed to 'Z' --davidm 1/25/99.

	for (str=buf ; *fmt ; ++fmt){
		if (*fmt != '%'){
			*str++ = *fmt;
			continue;
		}
			
		// process flags */
		flags = 0;
		repeat:
			++fmt;		// this also skips first '%'.
			switch (*fmt){
				case '-': flags |= LEFT; goto repeat;
				case '+': flags |= PLUS; goto repeat;
				case ' ': flags |= SPACE; goto repeat;
				case '#': flags |= SPECIAL; goto repeat;
				case '0': flags |= ZEROPAD; goto repeat;
			}
		
		// get field width.
		field_width = -1;
		if (isdigit(*fmt))
			field_width = skip_atoi(&fmt);
		else if (*fmt == '*'){
			++fmt;
			// it's the next argument.
			field_width = va_arg(args, int);
			if (field_width < 0) {
				field_width = -field_width;
				flags |= LEFT;
			}
		}

		// get the precision.
		precision = -1;
		if (*fmt == '.'){
			++fmt;	
			if (isdigit(*fmt))
				precision = skip_atoi(&fmt);
			else if (*fmt == '*'){
				++fmt;
				// it's the next argument.
				precision = va_arg(args, int);
			}
			if (precision < 0)
				precision = 0;
		}

		/* get the conversion qualifier */
		qualifier = -1;
		if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L' || *fmt =='Z'){
			qualifier = *fmt;
			++fmt;
		}

		/* default base */
		base = 10;

		switch (*fmt){
			case 'c':
				if (!(flags & LEFT))
					while (--field_width > 0)
						*str++ = ' ';
				*str++ = (unsigned char) va_arg(args, int);
				while (--field_width > 0)
					*str++ = ' ';
				continue;
	
			case 's':
				s = va_arg(args, char *);
				if (!s)
					s = "<NULL>";
	
				len = strnlen(s, precision);
	
				if (!(flags & LEFT))
					while (len < field_width--)
						*str++ = ' ';
				for (i = 0; i < len; ++i)
					*str++ = *s++;
				while (len < field_width--)
					*str++ = ' ';
				continue;
			case 'p':
				if (field_width == -1){
					field_width = 2*sizeof(void *);
					flags |= ZEROPAD;
				}
				str = number(str, (unsigned long) va_arg(args, void *), 16, field_width, precision, flags);
				continue;
			case 'n':
				if (qualifier == 'l'){
					long * ip = va_arg(args, long *);
					*ip = (str - buf);
				} else if (qualifier == 'Z'){
					uint * ip = va_arg(args, uint *);
					*ip = (str - buf);
				} else {
					int * ip = va_arg(args, int *);
					*ip = (str - buf);
				}
				continue;
			case '%':
				*str++ = '%';
				continue;
			case 'o':		// integer number formats - set up the flags and "break".
				base = 8;
				break;
			case 'X':
				flags |= LARGE;
			case 'x':
				base = 16;
				break;
			case 'd':
			case 'i':
				flags |= SIGN;
			case 'u':
				break;
			default:
				*str++ = '%';
				if (*fmt)	*str++ = *fmt;
				else		--fmt;
				continue;
		}
		if (qualifier == 'L')
			num = va_arg(args, long long);
		else if (qualifier == 'l'){
			num = va_arg(args, unsigned long);
			if (flags & SIGN)
				num = (signed long) num;
		} else if (qualifier == 'Z'){
			num = va_arg(args, uint);
		} else if (qualifier == 'h'){
			num = (unsigned short) va_arg(args, int);
			if (flags & SIGN)
				num = (signed short) num;
		} else {
			num = va_arg(args, unsigned int);
			if (flags & SIGN)
				num = (signed int) num;
		}
		str = number(str, num, base, field_width, precision, flags);
	}
	*str = '\0';
	return str-buf;
}

/**
 * sprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @fmt: The format string to use
 * @...: Arguments for the format string
 */
int sprintf(char *buf, const char *fmt, ...){
	va_list args;
	int i;

	va_start(args, fmt);
	i=vsprintf(buf,fmt,args);
	va_end(args);
	return i;
}