From 9f46a3aeffd6bbaff03610129924f85e44e82280 Mon Sep 17 00:00:00 2001
From: John Hodge <tpg@mutabah.net>
Date: Fri, 15 Feb 2013 10:43:05 +0800
Subject: [PATCH] Usermode/libc - ftoa() fixes, current test set passes

---
 Usermode/Libraries/Makefile.tpl              |  2 +-
 Usermode/Libraries/libc.so_src/Makefile      |  2 +-
 Usermode/Libraries/libc.so_src/TEST_printf.c |  5 ++--
 Usermode/Libraries/libc.so_src/printf.c      | 31 ++++++++++++++++----
 4 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/Usermode/Libraries/Makefile.tpl b/Usermode/Libraries/Makefile.tpl
index 21f805cb..f0084e21 100644
--- a/Usermode/Libraries/Makefile.tpl
+++ b/Usermode/Libraries/Makefile.tpl
@@ -78,7 +78,7 @@ $(OUTPUTDIR)Libs/%:
 
 obj-native/%.no: %.c
 	@mkdir -p $(dir $@)
-	$(NCC) -c $< -o $@ -MD -MP -MF $@.dep
+	$(NCC) -c $< -o $@ -Wall -std=gnu99 -MD -MP -MF $@.dep
 
 TEST_%: obj-native/TEST_%.no obj-native/%.no
 	$(NCC) -o $@ $^
diff --git a/Usermode/Libraries/libc.so_src/Makefile b/Usermode/Libraries/libc.so_src/Makefile
index 2e4e2b2c..0fd1e5be 100644
--- a/Usermode/Libraries/libc.so_src/Makefile
+++ b/Usermode/Libraries/libc.so_src/Makefile
@@ -25,4 +25,4 @@ EXP_%.txt: TEST_%.native
 	rm TEST_printf.native
 
 %.native: %.c
-	$(NCC) $< -o $@ -Wall -Werror
+	$(NCC) $< -o $@ -Wall -std=gnu99
diff --git a/Usermode/Libraries/libc.so_src/TEST_printf.c b/Usermode/Libraries/libc.so_src/TEST_printf.c
index ed78fd68..fe251d9d 100644
--- a/Usermode/Libraries/libc.so_src/TEST_printf.c
+++ b/Usermode/Libraries/libc.so_src/TEST_printf.c
@@ -23,9 +23,10 @@ int main(int argc, char *argv[])
 	TST("Integer", "%u", 1234);
 	
 	TST("Float", "%f", 3.1414926535);
+	TST("Float", "%f", 10.0);
 	TST("Float", "%.10f", 3.1414926535);
-	TST("Float", "%e", 3.1414926535);
-	TST("Float", "%g", 3.1414926535);
+	TST("Float", "%e", 3.1415926535);
+	TST("Float", "%g", 3.1415926535);
 	TST("Float", "%E", 1000000000.00);
 	TST("Float", "%a", 16.0);
 	TST("Float", "%a", 1024.0);
diff --git a/Usermode/Libraries/libc.so_src/printf.c b/Usermode/Libraries/libc.so_src/printf.c
index f4b13a4a..bd67e00f 100644
--- a/Usermode/Libraries/libc.so_src/printf.c
+++ b/Usermode/Libraries/libc.so_src/printf.c
@@ -240,6 +240,13 @@ EXPORT int _vcprintf_int(printf_putch_t putch_cb, void *putch_h, const char *for
 			pos += _printf_ftoa(putch_cb, putch_h, arg_f, 10, FPN_SCI,
 				precision, 0, bJustifyLeft, c == 'E');
 			break;
+		// Scientific Float
+		case 'g':
+		case 'G':
+			arg_f = bLong ? va_arg(args, long double) : va_arg(args, double);
+			pos += _printf_ftoa(putch_cb, putch_h, arg_f, 10, FPN_SHORTEST,
+				precision, 0, bJustifyLeft, c == 'G');
+			break;
 		// Hexadecimal Scientific
 		case 'a':
 		case 'A':
@@ -632,12 +639,24 @@ size_t _printf_ftoa(printf_putch_t putch_cb, void *putch_h, long double num, siz
 	{
 		//TODO:
 		//int	first_set_sig = BSL(significand);
-	//	TODO: if( num > pos(Base, 2+Precision+2+log_base(exponent) )
-		Notation = FPN_SCI;
+		// bSign+log10(num)+1+precision vs. bSign+1+1+precision+1+1+log10(exponent)
+		 int	log10_num = exponent * 301 / 1000;	// log_10(2) = 0.30102999566...
+		 int	log10_exp10 = 2;
+		 int	sci_len = (signisneg || bForceSign) + 2 + (Precision-1) + 2 + log10_exp10;
+		 int	std_whole_len = (log10_num > 0 ? log10_num : 1);
+		 int	std_len = (signisneg || bForceSign) + std_whole_len + 1 + (Precision-std_whole_len);
+		if( sci_len > std_len ) {
+			Precision -= std_whole_len;
+			Notation = FPN_STD;
+		}
+		else {
+			Precision -= 1;
+			Notation = FPN_SCI;
+		}
 	}
 
 	double precision_max = 1;
-	while(Precision--)
+	for(int i = Precision; i--; )
 		precision_max /= Base;
 
 	// Determine scientific's exponent and starting denominator
@@ -669,7 +688,7 @@ size_t _printf_ftoa(printf_putch_t putch_cb, void *putch_h, long double num, siz
 	}
 	else
 	{
-		while( den < num )
+		while( den <= num )
 			den *= Base;
 		den /= Base;
 	}
@@ -694,10 +713,10 @@ size_t _printf_ftoa(printf_putch_t putch_cb, void *putch_h, long double num, siz
 	} while( den >= 1 );
 
 	// Decimal point (if needed/forced)	
-	if( den >= precision_max || bForcePoint )
+	if( Precision > 0 || bForcePoint )
 		_putch('.');
 	// Decimal section
-	while( den >= precision_max )
+	for(int i = Precision; i--; )
 	{
 		num = _longdiv(num, den, &value);
 		_putch(cDIGITS[value]);
-- 
2.20.1