From cc5302af315d7493a8c75deb499cae80599eab60 Mon Sep 17 00:00:00 2001
From: Jonas 'Sortie' Termansen <sortie@maxsi.org>
Date: Tue, 19 Mar 2013 22:10:27 +0100
Subject: [PATCH] Add atof(3).

---
 libc/Makefile         |  1 +
 libc/atof.cpp         | 81 +++++++++++++++++++++++++++++++++++++++++++
 libc/include/stdlib.h |  2 +-
 3 files changed, 83 insertions(+), 1 deletion(-)
 create mode 100644 libc/atof.cpp

diff --git a/libc/Makefile b/libc/Makefile
index f1cd1b44..6ee8c199 100644
--- a/libc/Makefile
+++ b/libc/Makefile
@@ -20,6 +20,7 @@ FREEOBJS=\
 abort.o \
 abs.o \
 _assert.o \
+atof.o \
 atoi.o \
 atoll.o \
 atol.o \
diff --git a/libc/atof.cpp b/libc/atof.cpp
new file mode 100644
index 00000000..fa1be629
--- /dev/null
+++ b/libc/atof.cpp
@@ -0,0 +1,81 @@
+/*******************************************************************************
+
+    Copyright(C) Jonas 'Sortie' Termansen 2013.
+
+    This file is part of the Sortix C Library.
+
+    The Sortix C Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or (at your
+    option) any later version.
+
+    The Sortix C Library is distributed in the hope that it will be useful, but
+    WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+    or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
+
+    atof.cpp
+    Converts floats represented as strings to binary representation.
+
+*******************************************************************************/
+
+#include <stdlib.h>
+#include <stdio.h>
+
+// TODO: This horribly hacky code is taken from sdlquake's common.c, which is
+//       licensed under the GPL. Since most Sortix software is GPL-compatible
+//       this will do for now. It's a temporary measure until I get around to
+//       writing a real strtod function - most of them are true horrors.
+
+extern "C" double atof(const char* str)
+{
+	int sign = *str == '-' ? (str++, -1) : 1;
+	double val = 0.0;
+
+	if ( str[0] == '0' && (str[1] == 'x' || str[1] == 'X') )
+	{
+		str += 2;
+		while ( true )
+		{
+			char c = *str++;
+			if ( '0' <= c && c <= '9' )
+				val = val * 16 + c - '0';
+			else if ( 'a' <= c && c <= 'f' )
+				val = val * 16 + c - 'a' + 10;
+			else if ( 'A' <= c && c <= 'F' )
+				val = val * 16 + c - 'A' + 10;
+			else
+				return val * sign;
+		}
+	}
+
+	int decimal = -1;
+	int total = 0;
+	while ( true )
+	{
+		char c = *str++;
+		if (c == '.')
+		{
+			decimal = total;
+			continue;
+		}
+		if ( c < '0' || c > '9' )
+			break;
+		val = val * 10 + c - '0';
+		total++;
+	}
+
+	if ( decimal == -1 )
+		return val * sign;
+
+	while ( decimal < total )
+	{
+		val /= 10;
+		total--;
+	}
+
+	return val * sign;
+}
diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index 081ed2f1..48427457 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -64,6 +64,7 @@ typedef struct
 void abort(void) __attribute__ ((__noreturn__));
 int abs(int value);
 int atexit(void (*function)(void));
+double atof(const char* value);
 int atoi(const char*);
 long atol(const char*);
 long long atoll(const char*);
@@ -120,7 +121,6 @@ int clearenv(void);
 /* TODO: These are not implemented in sortix libc yet. */
 #if defined(__SORTIX_SHOW_UNIMPLEMENTED)
 long a64l(const char* s);
-double atof(const char* value);
 double drand48(void);
 double erand48(unsigned short [3]);
 int getsubopt(char**, char* const *, char**);