aml/aml_vsnprintf.c

/*
 * Copyright (c) 2021-2022 Amlogic, Inc. All rights reserved.
 *
 * SPDX-License-Identifier: MIT
 */

#include <stdio.h>
#include <stdarg.h>
#include "aml_vsnprintf.h"

#include "aml_strnlen.h"
#include "aml_isdigit.h"
#include <stdarg.h>
#include <stddef.h>

#if CONFIG_LIBC_AML_FLOAT_PRINT
#define HAS_FLOAT 1
#else
#define HAS_FLOAT 0
#endif

#define ZEROPAD (1 << 0) /* Pad with zero */
#define SIGN (1 << 1) /* Unsigned/signed long */
#define PLUS (1 << 2) /* Show plus */
#define SPACE (1 << 3) /* Spacer */
#define LEFT (1 << 4) /* Left justified */
#define HEX_PREP (1 << 5) /* 0x */
#define UPPERCASE (1 << 6) /* 'ABCDEF' */

static char *digits = "0123456789abcdefghijklmnopqrstuvwxyz";
static char *upper_digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

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

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

	return i;
}

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

	if (type & UPPERCASE)
		dig = upper_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 & HEX_PREP) {
		if (base == 16)
			size -= 2;
		else if (base == 8)
			size--;
	}

	i = 0;

	if (num == 0)
		tmp[i++] = '0';
	else {
		while (num != 0) {
			tmp[i++] = dig[((unsigned long)num) % (unsigned int)base];
			num = ((unsigned long)num) / (unsigned int)base;
		}
	}

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

	if (type & HEX_PREP) {
		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;
}

static char *eaddr(char *str, unsigned char *addr, int size, int precision, int type)
{
	char tmp[24];
	char *dig = digits;
	int i, len;

	if (type & UPPERCASE)
		dig = upper_digits;
	len = 0;
	for (i = 0; i < 6; i++) {
		if (i != 0)
			tmp[len++] = ':';
		tmp[len++] = dig[addr[i] >> 4];
		tmp[len++] = dig[addr[i] & 0x0F];
	}

	if (!(type & LEFT))
		while (len < size--)
			*str++ = ' ';
	for (i = 0; i < len; ++i)
		*str++ = tmp[i];
	while (len < size--)
		*str++ = ' ';

	return str;
}

static char *iaddr(char *str, unsigned char *addr, int size, int precision, int type)
{
	char tmp[24];
	int i, n, len;

	len = 0;
	for (i = 0; i < 4; i++) {
		if (i != 0)
			tmp[len++] = '.';
		n = addr[i];

		if (n == 0)
			tmp[len++] = digits[0];
		else {
			if (n >= 100) {
				tmp[len++] = digits[n / 100];
				n = n % 100;
				tmp[len++] = digits[n / 10];
				n = n % 10;
			} else if (n >= 10) {
				tmp[len++] = digits[n / 10];
				n = n % 10;
			}

			tmp[len++] = digits[n];
		}
	}

	if (!(type & LEFT))
		while (len < size--)
			*str++ = ' ';
	for (i = 0; i < len; ++i)
		*str++ = tmp[i];
	while (len < size--)
		*str++ = ' ';

	return str;
}

char *ecvtbuf(double arg, int ndigits, int *decpt, int *sign, char *buf);
char *fcvtbuf(double arg, int ndigits, int *decpt, int *sign, char *buf);
static void ee_bufcpy(char *d, char *s, int count);

void ee_bufcpy(char *pd, char *ps, int count)
{
	char *pe = ps + count;

	while (ps != pe)
		*pd++ = *ps++;
}

static void parse_float(double value, char *buffer, char fmt, int precision)
{
	int decpt, sign, exp, pos;
	char *digits = NULL;
	char cvtbuf[80];
	int capexp = 0;
	int magnitude;

	if (fmt == 'G' || fmt == 'E') {
		capexp = 1;
		fmt += 'a' - 'A';
	}

	if (fmt == 'g') {
		digits = ecvtbuf(value, precision, &decpt, &sign, cvtbuf);
		magnitude = decpt - 1;
		if (magnitude < -4 || magnitude > precision - 1) {
			fmt = 'e';
			precision -= 1;
		} else {
			fmt = 'f';
			precision -= decpt;
		}
	}

	if (fmt == 'e') {
		digits = ecvtbuf(value, precision + 1, &decpt, &sign, cvtbuf);

		if (sign)
			*buffer++ = '-';
		*buffer++ = *digits;
		if (precision > 0)
			*buffer++ = '.';
		ee_bufcpy(buffer, digits + 1, precision);
		buffer += precision;
		*buffer++ = capexp ? 'E' : 'e';

		if (decpt == 0) {
			if (value == 0.0)
				exp = 0;
			else
				exp = -1;
		} else
			exp = decpt - 1;

		if (exp < 0) {
			*buffer++ = '-';
			exp = -exp;
		} else
			*buffer++ = '+';

		buffer[2] = (exp % 10) + '0';
		exp = exp / 10;
		buffer[1] = (exp % 10) + '0';
		exp = exp / 10;
		buffer[0] = (exp % 10) + '0';
		buffer += 3;
	} else if (fmt == 'f') {
		digits = fcvtbuf(value, precision, &decpt, &sign, cvtbuf);
		if (sign)
			*buffer++ = '-';
		if (*digits) {
			if (decpt <= 0) {
				*buffer++ = '0';
				*buffer++ = '.';
				for (pos = 0; pos < -decpt; pos++)
					*buffer++ = '0';
				while (*digits)
					*buffer++ = *digits++;
			} else {
				pos = 0;
				while (*digits) {
					if (pos++ == decpt)
						*buffer++ = '.';
					*buffer++ = *digits++;
				}
			}
		} else {
			*buffer++ = '0';
			if (precision > 0) {
				*buffer++ = '.';
				for (pos = 0; pos < precision; pos++)
					*buffer++ = '0';
			}
		}
	}

	*buffer = '\0';
}

static void decimal_point(char *buffer)
{
	while (*buffer) {
		if (*buffer == '.')
			return;
		if (*buffer == 'e' || *buffer == 'E')
			break;
		buffer++;
	}

	if (*buffer) {
		int n = strnlen(buffer, 256);

		while (n > 0) {
			buffer[n + 1] = buffer[n];
			n--;
		}

		*buffer = '.';
	} else {
		*buffer++ = '.';
		*buffer = '\0';
	}
}

static void cropzeros(char *buffer)
{
	char *stop;

	while (*buffer && *buffer != '.')
		buffer++;
	if (*buffer++) {
		while (*buffer && *buffer != 'e' && *buffer != 'E')
			buffer++;
		stop = buffer--;
		while (*buffer == '0')
			buffer--;
		if (*buffer == '.')
			buffer--;
		while (buffer != stop)
			*++buffer = 0;
	}
}

static char *flt(char *str, double num, int size, int precision, char fmt, int flags)
{
	char tmp[80];
	char c, sign;
	int n, i;

	// Left align means no zero padding
	if (flags & LEFT)
		flags &= ~ZEROPAD;

	// Determine padding and sign char
	c = (flags & ZEROPAD) ? '0' : ' ';
	sign = 0;
	if (flags & SIGN) {
		if (num < 0.0) {
			sign = '-';
			num = -num;
			size--;
		} else if (flags & PLUS) {
			sign = '+';
			size--;
		} else if (flags & SPACE) {
			sign = ' ';
			size--;
		}
	}

	// Compute the precision value
	if (precision < 0)
		precision = 6; // Default precision: 6

	// Convert floating point number to text
	parse_float(num, tmp, fmt, precision);

	if ((flags & HEX_PREP) && precision == 0)
		decimal_point(tmp);
	if (fmt == 'g' && !(flags & HEX_PREP))
		cropzeros(tmp);

	n = strnlen(tmp, 256);

	// Output number with alignment and padding
	size -= n;
	if (!(flags & (ZEROPAD | LEFT)))
		while (size-- > 0)
			*str++ = ' ';
	if (sign)
		*str++ = sign;
	if (!(flags & LEFT))
		while (size-- > 0)
			*str++ = c;
	for (i = 0; i < n; i++)
		*str++ = tmp[i];
	while (size-- > 0)
		*str++ = ' ';

	return str;
}

int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
	int len;
	unsigned long num;
	int i, base;
	char *str;
	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

	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 |= HEX_PREP;
			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++;
			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;
				precision = va_arg(args, int);
			}
			if (precision < 0)
				precision = 0;
		}

		// Get the conversion qualifier
		qualifier = -1;
		if (*fmt == 'l' || *fmt == 'L') {
			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, size - (str-buf) - 1);
			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 'A':
			flags |= UPPERCASE;

		case 'a':
			if (qualifier == 'l')
				str = eaddr(str, va_arg(args, unsigned char *), field_width,
					precision, flags);
			else
				str = iaddr(str, va_arg(args, unsigned char *), field_width,
					precision, flags);
			continue;

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

		case 'X':
			flags |= UPPERCASE;

		case 'x':
			base = 16;
			break;

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

		case 'u':
			break;

#if HAS_FLOAT
		case 'f':
			str = flt(str, va_arg(args, double), field_width, precision, *fmt,
				flags | SIGN);
			continue;

#endif

		default:
			if (*fmt != '%')
				*str++ = '%';
			if (*fmt)
				*str++ = *fmt;
			else
				--fmt;
			continue;
		}

		if (qualifier == 'l')
			num = va_arg(args, unsigned long);
		else if (flags & SIGN)
			num = va_arg(args, int);
		else
			num = va_arg(args, unsigned int);

		str = number(str, num, base, field_width, precision, flags);
	}

	*str = '\0';
	return str - buf;
}