Index: uspace/lib/posix/source/stdlib/strtold.c
===================================================================
--- uspace/lib/posix/source/stdlib/strtold.c	(revision 33c29521d96b892e096419a2fd8beb867e2596f6)
+++ uspace/lib/posix/source/stdlib/strtold.c	(revision 33c29521d96b892e096419a2fd8beb867e2596f6)
@@ -0,0 +1,491 @@
+/*
+ * Copyright (c) 2011 Jiri Zarevucky
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libposix
+ * @{
+ */
+/** @file Backend for floating point conversions.
+ */
+
+#define LIBPOSIX_INTERNAL
+
+/* Must be first. */
+#include "posix/stdbool.h"
+
+#include "../internal/common.h"
+#include "posix/stdlib.h"
+
+#include "posix/assert.h"
+#include "posix/ctype.h"
+#include "posix/stdint.h"
+#include "posix/strings.h"
+#include "posix/errno.h"
+#include "posix/limits.h"
+
+#include "posix/float.h"
+
+#ifndef HUGE_VALL
+	#define HUGE_VALL (+1.0l / +0.0l)
+#endif
+
+#ifndef abs
+	#define abs(x) (((x) < 0) ? -(x) : (x))
+#endif
+
+/* If the constants are not defined, use double precision as default. */
+#ifndef LDBL_MANT_DIG
+	#define LDBL_MANT_DIG 53
+#endif
+#ifndef LDBL_MAX_EXP
+	#define LDBL_MAX_EXP 1024
+#endif
+#ifndef LDBL_MIN_EXP
+	#define LDBL_MIN_EXP (-1021)
+#endif
+#ifndef LDBL_DIG
+	#define LDBL_DIG 15
+#endif
+#ifndef LDBL_MIN
+	#define LDBL_MIN 2.2250738585072014E-308
+#endif
+
+/* power functions ************************************************************/
+
+#if LDBL_MAX_EXP >= 16384
+const int MAX_POW5 = 12;
+#else
+const int MAX_POW5 = 8;
+#endif
+
+/* The value at index i is approximately 5**(2**i). */
+long double pow5[] = {
+	0x5p0l,
+	0x19p0l,
+	0x271p0l,
+	0x5F5E1p0l,
+	0x2386F26FC1p0l,
+	0x4EE2D6D415B85ACEF81p0l,
+	0x184F03E93FF9F4DAA797ED6E38ED6p36l,
+	0x127748F9301D319BF8CDE66D86D62p185l,
+	0x154FDD7F73BF3BD1BBB77203731FDp482l,
+#if LDBL_MAX_EXP >= 16384
+	0x1C633415D4C1D238D98CAB8A978A0p1076l,
+	0x192ECEB0D02EA182ECA1A7A51E316p2265l,
+	0x13D1676BB8A7ABBC94E9A519C6535p4643l,
+	0x188C0A40514412F3592982A7F0094p9398l,
+#endif
+};
+
+#if LDBL_MAX_EXP >= 16384
+const int MAX_POW2 = 15;
+#else
+const int MAX_POW2 = 9;
+#endif
+
+/* Powers of two. */
+long double pow2[] = {
+	0x1P1l,
+	0x1P2l,
+	0x1P4l,
+	0x1P8l,
+	0x1P16l,
+	0x1P32l,
+	0x1P64l,
+	0x1P128l,
+	0x1P256l,
+	0x1P512l,
+#if LDBL_MAX_EXP >= 16384
+	0x1P1024l,
+	0x1P2048l,
+	0x1P4096l,
+	0x1P8192l,
+#endif
+};
+
+/**
+ * Multiplies a number by a power of five.
+ * The result may be inexact and may not be the best possible approximation.
+ *
+ * @param mant Number to be multiplied.
+ * @param exp Base 5 exponent.
+ * @return mant multiplied by 5**exp
+ */
+static long double mul_pow5(long double mant, int exp)
+{
+	if (mant == 0.0l || mant == HUGE_VALL) {
+		return mant;
+	}
+	
+	if (abs(exp) >> (MAX_POW5 + 1) != 0) {
+		/* Too large exponent. */
+		errno = ERANGE;
+		return exp < 0 ? LDBL_MIN : HUGE_VALL;
+	}
+	
+	if (exp < 0) {
+		exp = abs(exp);
+		for (int bit = 0; bit <= MAX_POW5; ++bit) {
+			/* Multiply by powers of five bit-by-bit. */
+			if (((exp >> bit) & 1) != 0) {
+				mant /= pow5[bit];
+				if (mant == 0.0l) {
+					/* Underflow. */
+					mant = LDBL_MIN;
+					errno = ERANGE;
+					break;
+				}
+			}
+		}
+	} else {
+		for (int bit = 0; bit <= MAX_POW5; ++bit) {
+			/* Multiply by powers of five bit-by-bit. */
+			if (((exp >> bit) & 1) != 0) {
+				mant *= pow5[bit];
+				if (mant == HUGE_VALL) {
+					/* Overflow. */
+					errno = ERANGE;
+					break;
+				}
+			}
+		}
+	}
+	
+	return mant;
+}
+
+/**
+ * Multiplies a number by a power of two. This is always exact.
+ *
+ * @param mant Number to be multiplied.
+ * @param exp Base 2 exponent.
+ * @return mant multiplied by 2**exp.
+ */
+static long double mul_pow2(long double mant, int exp)
+{
+	if (mant == 0.0l || mant == HUGE_VALL) {
+		return mant;
+	}
+	
+	if (exp > LDBL_MAX_EXP || exp < LDBL_MIN_EXP) {
+		errno = ERANGE;
+		return exp < 0 ? LDBL_MIN : HUGE_VALL;
+	}
+	
+	if (exp < 0) {
+		exp = abs(exp);
+		for (int i = 0; i <= MAX_POW2; ++i) {
+			if (((exp >> i) & 1) != 0) {
+				mant /= pow2[i];
+				if (mant == 0.0l) {
+					mant = LDBL_MIN;
+					errno = ERANGE;
+					break;
+				}
+			}
+		}
+	} else {
+		for (int i = 0; i <= MAX_POW2; ++i) {
+			if (((exp >> i) & 1) != 0) {
+				mant *= pow2[i];
+				if (mant == HUGE_VALL) {
+					errno = ERANGE;
+					break;
+				}
+			}
+		}
+	}
+	
+	return mant;
+}
+
+/* end power functions ********************************************************/
+
+
+
+/**
+ * Convert decimal string representation of the floating point number.
+ * Function expects the string pointer to be already pointed at the first
+ * digit (i.e. leading optional sign was already consumed by the caller).
+ * 
+ * @param sptr Pointer to the storage of the string pointer. Upon successful
+ *     conversion, the string pointer is updated to point to the first
+ *     unrecognized character.
+ * @return An approximate representation of the input floating-point number.
+ */
+static long double parse_decimal(const char **sptr)
+{
+	assert(sptr != NULL);
+	assert (*sptr != NULL);
+	
+	const int DEC_BASE = 10;
+	const char DECIMAL_POINT = '.';
+	const char EXPONENT_MARK = 'e';
+	
+	const char *str = *sptr;
+	long double significand = 0;
+	long exponent = 0;
+	
+	/* number of digits parsed so far */
+	int parsed_digits = 0;
+	bool after_decimal = false;
+	
+	while (isdigit(*str) || (!after_decimal && *str == DECIMAL_POINT)) {
+		if (*str == DECIMAL_POINT) {
+			after_decimal = true;
+			str++;
+			continue;
+		}
+		
+		if (parsed_digits == 0 && *str == '0') {
+			/* Nothing, just skip leading zeros. */
+		} else if (parsed_digits < LDBL_DIG) {
+			significand = significand * DEC_BASE + (*str - '0');
+			parsed_digits++;
+		} else {
+			exponent++;
+		}
+		
+		if (after_decimal) {
+			/* Decrement exponent if we are parsing the fractional part. */
+			exponent--;
+		}
+		
+		str++;
+	}
+	
+	/* exponent */
+	if (tolower(*str) == EXPONENT_MARK) {
+		str++;
+		
+		/* Returns MIN/MAX value on error, which is ok. */
+		long exp = strtol(str, (char **) &str, DEC_BASE);
+		
+		if (exponent > 0 && exp > LONG_MAX - exponent) {
+			exponent = LONG_MAX;
+		} else if (exponent < 0 && exp < LONG_MIN - exponent) {
+			exponent = LONG_MIN;
+		} else {
+			exponent += exp;
+		}
+	}
+	
+	*sptr = str;
+	
+	/* Return multiplied by a power of ten. */
+	return mul_pow2(mul_pow5(significand, exponent), exponent);
+}
+
+/**
+ * Derive a hexadecimal digit from its character representation.
+ * 
+ * @param ch Character representation of the hexadecimal digit.
+ * @return Digit value represented by an integer.
+ */
+static inline int hex_value(char ch)
+{
+	if (ch <= '9') {
+		return ch - '0';
+	} else {
+		return 10 + tolower(ch) - 'a';
+	}
+}
+
+/**
+ * Convert hexadecimal string representation of the floating point number.
+ * Function expects the string pointer to be already pointed at the first
+ * digit (i.e. leading optional sign and 0x prefix were already consumed
+ * by the caller).
+ *
+ * @param sptr Pointer to the storage of the string pointer. Upon successful
+ *     conversion, the string pointer is updated to point to the first
+ *     unrecognized character.
+ * @return Representation of the input floating-point number.
+ */
+static long double parse_hexadecimal(const char **sptr)
+{
+	assert(sptr != NULL && *sptr != NULL);
+	
+	const int DEC_BASE = 10;
+	const int HEX_BASE = 16;
+	const char DECIMAL_POINT = '.';
+	const char EXPONENT_MARK = 'p';
+	
+	const char *str = *sptr;
+	long double significand = 0;
+	long exponent = 0;
+	
+	/* number of bits parsed so far */
+	int parsed_bits = 0;
+	bool after_decimal = false;
+	
+	while (posix_isxdigit(*str) || (!after_decimal && *str == DECIMAL_POINT)) {
+		if (*str == DECIMAL_POINT) {
+			after_decimal = true;
+			str++;
+			continue;
+		}
+		
+		if (parsed_bits == 0 && *str == '0') {
+			/* Nothing, just skip leading zeros. */
+		} else if (parsed_bits <= LDBL_MANT_DIG) {
+			significand = significand * HEX_BASE + hex_value(*str);
+			parsed_bits += 4;
+		} else {
+			exponent += 4;
+		}
+		
+		if (after_decimal) {
+			exponent -= 4;
+		}
+		
+		str++;
+	}
+	
+	/* exponent */
+	if (tolower(*str) == EXPONENT_MARK) {
+		str++;
+		
+		/* Returns MIN/MAX value on error, which is ok. */
+		long exp = strtol(str, (char **) &str, DEC_BASE);
+		
+		if (exponent > 0 && exp > LONG_MAX - exponent) {
+			exponent = LONG_MAX;
+		} else if (exponent < 0 && exp < LONG_MIN - exponent) {
+			exponent = LONG_MIN;
+		} else {
+			exponent += exp;
+		}
+	}
+	
+	*sptr = str;
+	
+	/* Return multiplied by a power of two. */
+	return mul_pow2(significand, exponent);
+}
+
+/**
+ * Converts a string representation of a floating-point number to
+ * its native representation. Largely POSIX compliant, except for
+ * locale differences (always uses '.' at the moment) and rounding.
+ * Decimal strings are NOT guaranteed to be correctly rounded. This function
+ * should return a good enough approximation for most purposes but if you
+ * depend on a precise conversion, use hexadecimal representation.
+ * Hexadecimal strings are currently always rounded towards zero, regardless
+ * of the current rounding mode.
+ *
+ * @param nptr Input string.
+ * @param endptr If non-NULL, *endptr is set to the position of the first
+ *     unrecognized character.
+ * @return An approximate representation of the input floating-point number.
+ */
+long double posix_strtold(const char *restrict nptr, char **restrict endptr)
+{
+	assert(nptr != NULL);
+	
+	const int RADIX = '.';
+	
+	/* minus sign */
+	bool negative = false;
+	/* current position in the string */
+	int i = 0;
+	
+	/* skip whitespace */
+	while (isspace(nptr[i])) {
+		i++;
+	}
+	
+	/* parse sign */
+	switch (nptr[i]) {
+	case '-':
+		negative = true;
+		/* fallthrough */
+	case '+':
+		i++;
+	}
+	
+	/* check for NaN */
+	if (posix_strncasecmp(&nptr[i], "nan", 3) == 0) {
+		// FIXME: return NaN
+		// TODO: handle the parenthesised case
+		
+		if (endptr != NULL) {
+			*endptr = (char *) nptr;
+		}
+		errno = EINVAL;
+		return 0;
+	}
+	
+	/* check for Infinity */
+	if (posix_strncasecmp(&nptr[i], "inf", 3) == 0) {
+		i += 3;
+		if (posix_strncasecmp(&nptr[i], "inity", 5) == 0) {
+			i += 5;
+		}
+		
+		if (endptr != NULL) {
+			*endptr = (char *) &nptr[i];
+		}
+		return negative ? -HUGE_VALL : +HUGE_VALL;
+	}
+
+	/* check for a hex number */
+	if (nptr[i] == '0' && tolower(nptr[i + 1]) == 'x' &&
+	    (posix_isxdigit(nptr[i + 2]) ||
+	    (nptr[i + 2] == RADIX && posix_isxdigit(nptr[i + 3])))) {
+		i += 2;
+		
+		const char *ptr = &nptr[i];
+		/* this call sets errno if appropriate. */
+		long double result = parse_hexadecimal(&ptr);
+		if (endptr != NULL) {
+			*endptr = (char *) ptr;
+		}
+		return negative ? -result : result;
+	}
+	
+	/* check for a decimal number */
+	if (isdigit(nptr[i]) || (nptr[i] == RADIX && isdigit(nptr[i + 1]))) {
+		const char *ptr = &nptr[i];
+		/* this call sets errno if appropriate. */
+		long double result = parse_decimal(&ptr);
+		if (endptr != NULL) {
+			*endptr = (char *) ptr;
+		}
+		return negative ? -result : result;
+	}
+	
+	/* nothing to parse */
+	if (endptr != NULL) {
+		*endptr = (char *) nptr;
+	}
+	errno = EINVAL;
+	return 0;
+}
+
+/** @}
+ */