printk.c

使用Linux ARM GCC编译器来编译

/*
 * printk.c
 *
 * printk for vivi
 *
 * Based from linux/include/asm-arm/div64.h linux/lib/vsprintf.c 
 *            linux/kernel/printk.c 
 *
 * Author: Yong-iL Joh <[e-mail]>
 * Date  : $Date: 2004/02/04 06:22:25 $ 
 *
 * $Revision: 1.1.1.1 $
 */

#include <config.h>
#include <stdarg.h>
#include <types.h>
#include <string.h>
#include <ctype.h>
#ifdef CONFIG_SERIAL
#include <serial.h>
#endif

#ifdef CONFIG_SERIAL
#define PUTC(x)		putc(x)
#else
#define PUTC(x)
#endif

/* We're not 64-bit, but... */
#define do_div(n,base)						\
({								\
	int __res;						\
	__res = ((unsigned long)n) % (unsigned int)base;	\
	n = ((unsigned long)n) / (unsigned int)base;		\
	__res;							\
})

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

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


/*
* strnlen - Find the length of a length-limited string
* @s: The string to be sized
* @count: The maximum number of bytes to search
*/
size_t strnlen(const char * s, size_t count)
{
	const char *sc;

	for (sc = s; count-- && *sc != '\0'; ++sc)
		/* nothing */;
	return sc - s; 
}


#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 * buf, char * end, long long num, int base, int size, int precision, int type)
{
	char c,sign,tmp[66];
	const char *digits;
	const char small_digits[] = "0123456789abcdefghijklmnopqrstuvwxyz";
	const char large_digits[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	int i;

	digits = (type & LARGE) ? large_digits : small_digits;
	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) {
			if (buf <= end)
				*buf = ' ';
			++buf;
		}
	}
	if (sign) {
		if (buf <= end)
			*buf = sign;
		++buf;
	}
	if (type & SPECIAL) {
		if (base==8) {
			if (buf <= end)
				*buf = '0';
			++buf;
		} else if (base==16) {
			if (buf <= end)
				*buf = '0';
			++buf;
			if (buf <= end)
				*buf = digits[33];
			++buf;
		}
	}
	if (!(type & LEFT)) {
		while (size-- > 0) {
			if (buf <= end)
				*buf = c;
			++buf;
		}
	}
	while (i < precision--) {
		if (buf <= end)
			*buf = '0';
		++buf;
	}
	while (i-- > 0) {
		if (buf <= end)
			*buf = tmp[i];
		++buf;
	}
	while (size-- > 0) {
		if (buf <= end)
			*buf = ' ';
		++buf;
	}
	return buf;
}

/**
* vsnprintf - Format a string and place it in a buffer
* @buf: The buffer to place the result into
* @size: The size of the buffer, including the trailing null space
* @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 snprintf instead.
 */
int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
	int len;
	unsigned long long num;
	int i, base;
	char *str, *end, c;
	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 */

	str = buf;
	end = buf + size - 1;

	if (end < buf - 1) {
		end = ((void *) -1);
		size = end - buf + 1;
	}

	for (; *fmt ; ++fmt) {
		if (*fmt != '%') {
			if (str <= end)
				*str = *fmt;
			++str;
			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;
			if (qualifier == 'l' && *fmt == 'l') {
				qualifier = 'L';
				++fmt;
			}
		}

		/* default base */
		base = 10;

		switch (*fmt) {
			case 'c':
				if (!(flags & LEFT)) {
					while (--field_width > 0) {
						if (str <= end)
							*str = ' ';
						++str;
					}
				}
				c = (unsigned char) va_arg(args, int);
				if (str <= end)
					*str = c;
				++str;
				while (--field_width > 0) {
					if (str <= end)
						*str = ' ';
					++str;
				}
				continue;

			case 's':
				s = va_arg(args, char *);
				if (!s)
					s = "<NULL>";

				len = strnlen(s, precision);

				if (!(flags & LEFT)) {
					while (len < field_width--) {
						if (str <= end)
							*str = ' ';
						++str;
					}
				}
				for (i = 0; i < len; ++i) {
					if (str <= end)
						*str = *s;
					++str; ++s;
				}
				while (len < field_width--) {
					if (str <= end)
						*str = ' ';
					++str;
				}
				continue;

			case 'p':
				if (field_width == -1) {
					field_width = 2*sizeof(void *);
					flags |= ZEROPAD;
				}
				str = number(str, end,
						(unsigned long) va_arg(args, void *),
						16, field_width, precision, flags);
				continue;


			case 'n':
				/* FIXME:
				* What does C99 say about the overflow case here? */
				if (qualifier == 'l') {
					long * ip = va_arg(args, long *);
					*ip = (str - buf);
				} else if (qualifier == 'Z') {
					size_t * ip = va_arg(args, size_t *);
					*ip = (str - buf);
				} else {
					int * ip = va_arg(args, int *);
					*ip = (str - buf);
				}
				continue;

			case '%':
				if (str <= end)
					*str = '%';
				++str;
				continue;

				/* integer number formats - set up the flags and "break" */
			case 'o':
				base = 8;
				break;

			case 'X':
				flags |= LARGE;
			case 'x':
				base = 16;
				break;

			case 'd':
			case 'i':
				flags |= SIGN;
			case 'u':
				break;

			default:
				if (str <= end)
					*str = '%';
				++str;
				if (*fmt) {
					if (str <= end)
						*str = *fmt;
					++str;
				} 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, size_t);
		} 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, end, num, base,
				field_width, precision, flags);
	}
	if (str <= end)
		*str = '\0';
	else if (size > 0)
		/* don't write out a null byte if the buf size is zero */
		*end = '\0';
	/* the trailing null byte doesn't count towards the total
	* ++str;
	*/
	return str-buf;
}

/*
 * This is printk.  It can be called from any context.  We want it to work.
 * 
 * We try to grab the console_sem.  If we succeed, it's easy - we log the output and
 * call the console drivers.  If we fail to get the semaphore we place the output
 * into the log buffer and return.  The current holder of the console_sem will
 * notice the new output in release_console_sem() and will send it to the
 * consoles before releasing the semaphore.
 *
 * One effect of this deferred printing is that code which calls printk() and
 * then changes console_loglevel may break. This is because console_loglevel
 * is inspected when the actual printing occurs.
 */
int printk(const char *fmt, ...)
{
	va_list args;
	int printed_len;
	char *p;
	static char printk_buf[1024];

	/* Emit the output into the temporary buffer */
	va_start(args, fmt);
	printed_len = vsnprintf(printk_buf, sizeof(printk_buf), fmt, args);
	va_end(args);

	/*
	 * Copy the output into log_buf.  If the caller didn't provide
	 * appropriate log level tags, we insert them here
	 */
	for (p = printk_buf; *p; p++) {
		if (*p == '\n')
			PUTC('\r');
		PUTC(*p);
	}

	return printed_len;
}