_fpmaxtostr.c

Axis 221 camera embedded programing interface

/* Copyright (C) 2004       Manuel Novoa III    <[e-mail]>
 *
 * GNU Library General Public License (LGPL) version 2 or later.
 *
 * Dedicated to Toni.  See uClibc/DEDICATION.mjn3 for details.
 */

#include "_stdio.h"
#include <printf.h>
#include <float.h>
#include <locale.h>
#include <bits/uClibc_fpmax.h>

typedef void (__fp_outfunc_t)(FILE *fp, intptr_t type, intptr_t len,
							  intptr_t buf);


/* Copyright (C) 2000, 2001, 2003      Manuel Novoa III
 *
 * Function: 
 *
 *     size_t _fpmaxtostr(FILE * fp, __fpmax_t x, struct printf_info *info,
 *                         __fp_outfunc_t fp_outfunc);
 *
 * This is derived from the old _dtostr, whic I wrote for uClibc to provide
 * floating point support for the printf functions.  It handles +/- infinity,
 * nan, and signed 0 assuming you have ieee arithmetic.  It also now handles
 * digit grouping (for the uClibc supported locales) and hexadecimal float
 * notation.  Finally, via the fp_outfunc parameter, it now supports wide
 * output.
 *
 * Notes:
 *
 * At most DECIMAL_DIG significant digits are kept.  Any trailing digits
 * are treated as 0 as they are really just the results of rounding noise
 * anyway.  If you want to do better, use an arbitary precision arithmetic
 * package.  ;-)
 *
 * It should also be fairly portable, as no assumptions are made about the
 * bit-layout of doubles.  Of course, that does make it less efficient than
 * it could be.
 *
 */

/*****************************************************************************/
/* Don't change anything that follows unless you know what you're doing.     */
/*****************************************************************************/
/* Fairly portable nan check.  Bitwise for i386 generated larger code.
 * If you have a better version, comment this out.
 */
#define isnan(x)             ((x) != (x))

/* Without seminumerical functions to examine the sign bit, this is
 * about the best we can do to test for '-0'.
 */
#define zeroisnegative(x)    ((1./(x)) < 0)

/*****************************************************************************/
/* Don't change anything that follows peroid!!!  ;-)                         */
/*****************************************************************************/
#ifdef __UCLIBC_HAS_HEXADECIMAL_FLOATS__
#if FLT_RADIX != 2
#error FLT_RADIX != 2 is not currently supported
#endif
#endif /* __UCLIBC_HAS_HEXADECIMAL_FLOATS__ */

#define NUM_HEX_DIGITS      ((FPMAX_MANT_DIG + 3)/ 4)

/* WARNING: Adjust _fp_out_wide() below if this changes! */
/* With 32 bit ints, we can get 9 decimal digits per block. */
#define DIGITS_PER_BLOCK     9
#define HEX_DIGITS_PER_BLOCK 8

/* Maximum number of subcases to output double is...
 *  0 - sign
 *  1 - padding and initial digit
 *  2 - digits left of the radix
 *  3 - 0s left of the radix        or   radix
 *  4 - radix                       or   digits right of the radix
 *  5 - 0s right of the radix
 *  6 - exponent
 *  7 - trailing space padding
 * although not all cases may occur.
 */
#define MAX_CALLS 8

/*****************************************************************************/

#define NUM_DIGIT_BLOCKS   ((DECIMAL_DIG+DIGITS_PER_BLOCK-1)/DIGITS_PER_BLOCK)
#define NUM_HEX_DIGIT_BLOCKS \
   ((NUM_HEX_DIGITS+HEX_DIGITS_PER_BLOCK-1)/HEX_DIGITS_PER_BLOCK)

/* WARNING: Adjust _fp_out_wide() below if this changes! */

/* extra space for '-', '.', 'e+###', and nul */
#define BUF_SIZE  ( 3 + NUM_DIGIT_BLOCKS * DIGITS_PER_BLOCK )

/*****************************************************************************/

static const char fmt[] = "inf\0INF\0nan\0NAN\0.\0,";

#define INF_OFFSET        0		/* must be 1st */
#define NAN_OFFSET        8		/* must be 2nd.. see hex sign handling */
#define DECPT_OFFSET     16
#define THOUSEP_OFFSET   18

#define EMPTY_STRING_OFFSET 3

/*****************************************************************************/
#if FPMAX_MAX_10_EXP < -FPMAX_MIN_10_EXP
#error scaling code can not handle FPMAX_MAX_10_EXP < -FPMAX_MIN_10_EXP
#endif

static const __fpmax_t exp10_table[] =
{
	1e1L, 1e2L, 1e4L, 1e8L, 1e16L, 1e32L,	/* floats */
#if FPMAX_MAX_10_EXP < 32
#error unsupported FPMAX_MAX_10_EXP (< 32).  ANSI/ISO C requires >= 37.
#endif
#if FPMAX_MAX_10_EXP >= 64
	1e64L,
#endif
#if FPMAX_MAX_10_EXP >= 128
	1e128L,
#endif
#if FPMAX_MAX_10_EXP >= 256
	1e256L,
#endif
#if FPMAX_MAX_10_EXP >= 512
	1e512L,
#endif
#if FPMAX_MAX_10_EXP >= 1024
	1e1024L,
#endif
#if FPMAX_MAX_10_EXP >= 2048
	1e2048L,
#endif
#if FPMAX_MAX_10_EXP >= 4096
	1e4096L
#endif
#if FPMAX_MAX_10_EXP >= 8192
#error unsupported FPMAX_MAX_10_EXP.  please increase table
#endif
};

#define EXP10_TABLE_SIZE     (sizeof(exp10_table)/sizeof(exp10_table[0]))
#define EXP10_TABLE_MAX      (1U<<(EXP10_TABLE_SIZE-1))

/*****************************************************************************/
#ifdef __UCLIBC_HAS_HEXADECIMAL_FLOATS__

#if FLT_RADIX != 2
#error FLT_RADIX != 2 is not currently supported
#endif

#if FPMAX_MAX_EXP < -FPMAX_MIN_EXP
#error scaling code can not handle FPMAX_MAX_EXP < -FPMAX_MIN_EXP
#endif

static const __fpmax_t exp16_table[] = {
	0x1.0p4L, 0x1.0p8L, 0x1.0p16L, 0x1.0p32L, 0x1.0p64L,
#if FPMAX_MAX_EXP >= 128
	0x1.0p128L,
#endif
#if FPMAX_MAX_EXP >= 256
	0x1.0p256L,
#endif
#if FPMAX_MAX_EXP >= 512
	0x1.0p512L,
#endif
#if FPMAX_MAX_EXP >= 1024
	0x1.0p1024L,
#endif
#if FPMAX_MAX_EXP >= 2048
	0x1.0p2048L,
#endif
#if FPMAX_MAX_EXP >= 4096
	0x1.0p4096L,
#endif
#if FPMAX_MAX_EXP >= 8192
	0x1.0p8192L,
#endif
#if FPMAX_MAX_EXP >= 16384
	0x1.0p16384L
#endif
#if FPMAX_MAX_EXP >= 32768 
#error unsupported FPMAX_MAX_EXP.  please increase table
#endif
};

#define EXP16_TABLE_SIZE     (sizeof(exp16_table)/sizeof(exp16_table[0]))
#define EXP16_TABLE_MAX      (1U<<(EXP16_TABLE_SIZE-1))

#endif /* __UCLIBC_HAS_HEXADECIMAL_FLOATS__ */
/*****************************************************************************/

#define FPO_ZERO_PAD    (0x80 | '0')
#define FPO_STR_WIDTH   (0x80 | ' ');
#define FPO_STR_PREC    'p'

size_t _fpmaxtostr(FILE * fp, __fpmax_t x, struct printf_info *info,
				   __fp_outfunc_t fp_outfunc)
{
#ifdef __UCLIBC_HAS_HEXADECIMAL_FLOATS__
	__fpmax_t lower_bnd;
	__fpmax_t upper_bnd = 1e9;
#endif /* __UCLIBC_HAS_HEXADECIMAL_FLOATS__ */
	uint_fast32_t digit_block;
#ifdef __UCLIBC_HAS_HEXADECIMAL_FLOATS__
	uint_fast32_t base = 10;
	const __fpmax_t *power_table;
	int dpb = DIGITS_PER_BLOCK;
	int ndb = NUM_DIGIT_BLOCKS;
	int nd = DECIMAL_DIG;
	int sufficient_precision = 0;
#endif /* __UCLIBC_HAS_HEXADECIMAL_FLOATS__ */
#ifdef __UCLIBC_HAS_GLIBC_DIGIT_GROUPING__
	int num_groups = 0;
	int initial_group;	   /* This does not need to be initialized. */
	int tslen;			   /* This does not need to be initialized. */
	int nblk2;			   /* This does not need to be initialized. */
	const char *ts;		   /* This does not need to be initialized. */
#endif /* __UCLIBC_HAS_GLIBC_DIGIT_GROUPING__ */
	int i, j;
	int round, o_exp;
	int exp, exp_neg;
	int width, preci;
	int cnt;
	char *s;
	char *e;
	intptr_t pc_fwi[3*MAX_CALLS];
	intptr_t *ppc;
	intptr_t *ppc_last;
#ifdef __UCLIBC_MJN3_ONLY__
#warning TODO: The size of exp_buf[] should really be determined by the float constants.
#endif /* __UCLIBC_MJN3_ONLY__ */
	char exp_buf[16];
	char buf[BUF_SIZE];
	char sign_str[6];			/* Last 2 are for 1st digit + nul. */
	char o_mode;
	char mode;


	width = info->width;
	preci = info->prec;
	mode = info->spec;

	*exp_buf = 'e';
	if ((mode|0x20) == 'a') {
#ifdef __UCLIBC_HAS_HEXADECIMAL_FLOATS__
		*exp_buf = 'p';
		if (preci < 0) {
			preci = NUM_HEX_DIGITS;
			sufficient_precision = 1;
		}
#else
		mode += ('g' - 'a');
#endif
	}

	if (preci < 0) {
		preci = 6;
	}

	*sign_str = '\0';
	if (PRINT_INFO_FLAG_VAL(info,showsign)) {
		*sign_str = '+';
	} else if (PRINT_INFO_FLAG_VAL(info,space)) {
		*sign_str = ' ';
	}

	*(sign_str+1) = 0;
	pc_fwi[5] = INF_OFFSET;
	if (isnan(x)) {				/* First, check for nan. */
		pc_fwi[5] = NAN_OFFSET;
		goto INF_NAN;
	}

	if (x == 0) {				/* Handle 0 now to avoid false positive. */
#if 1
		if (zeroisnegative(x)) { /* Handle 'signed' zero. */
			*sign_str = '-';
		}
#endif
		exp = -1;
		goto GENERATE_DIGITS;
	}

	if (x < 0) {				/* Convert negatives to positives. */
		*sign_str = '-';
		x = -x;
	}

	if (__FPMAX_ZERO_OR_INF_CHECK(x)) {	/* Inf since zero handled above. */
	INF_NAN:
		info->pad = ' ';
		ppc = pc_fwi + 6;
		pc_fwi[3] = FPO_STR_PREC;
		pc_fwi[4] = 3;
		if (mode < 'a') {
			pc_fwi[5] += 4;
		}
		pc_fwi[5] = (intptr_t)(fmt + pc_fwi[5]);
		goto EXIT_SPECIAL;
	}

#ifdef __UCLIBC_MJN3_ONLY__
#warning TODO: Clean up defines when hexadecimal float notation is unsupported.
#endif /* __UCLIBC_MJN3_ONLY__ */

#ifdef __UCLIBC_HAS_HEXADECIMAL_FLOATS__

	if ((mode|0x20) == 'a') {
		lower_bnd = 0x1.0p31L;
		upper_bnd = 0x1.0p32L;
		power_table = exp16_table;
		exp = HEX_DIGITS_PER_BLOCK - 1;
		i = EXP16_TABLE_SIZE;
		j = EXP16_TABLE_MAX;
		dpb = HEX_DIGITS_PER_BLOCK;
		ndb = NUM_HEX_DIGIT_BLOCKS;
		nd = NUM_HEX_DIGITS;
		base = 16;
	} else {
		lower_bnd = 1e8;
/* 		upper_bnd = 1e9; */
		power_table = exp10_table;
		exp = DIGITS_PER_BLOCK - 1;
		i = EXP10_TABLE_SIZE;
		j = EXP10_TABLE_MAX;
/* 		dpb = DIGITS_PER_BLOCK; */
/* 		ndb = NUM_DIGIT_BLOCKS; */
/* 		base = 10; */
	}



#else  /* __UCLIBC_HAS_HEXADECIMAL_FLOATS__ */

#define lower_bnd    1e8
#define upper_bnd    1e9
#define power_table  exp10_table
#define dpb          DIGITS_PER_BLOCK
#define base         10
#define ndb          NUM_DIGIT_BLOCKS
#define nd           DECIMAL_DIG

	exp = DIGITS_PER_BLOCK - 1;
	i = EXP10_TABLE_SIZE;
	j = EXP10_TABLE_MAX;

#endif /* __UCLIBC_HAS_HEXADECIMAL_FLOATS__ */

	exp_neg = 0;
	if (x < lower_bnd) {		/* Do we need to scale up or down? */
		exp_neg = 1;
	}

	do {
		--i;
		if (exp_neg) {
			if (x * power_table[i] < upper_bnd) {
				x *= power_table[i];
				exp -= j;
			}
		} else {
			if (x / power_table[i] >= lower_bnd) {
				x /= power_table[i];
				exp += j;
			}