Import sources from 2011-03-30 iso image

1 files changed, 41 insertions, 0 deletions

diff --git a/sys/src/ape/lib/ap/stdio/ftoa.c b/sys/src/ape/lib/ap/stdio/ftoa.c
new file mode 100755
index 000000000..b241d2d43
--- /dev/null
+++ b/sys/src/ape/lib/ap/stdio/ftoa.c
@@ -0,0 +1,41 @@
+#include <math.h>
+#include <stdlib.h>
+double pow10(int);
+#define	NDIG	18
+#define	NFTOA	(NDIG+4)
+/*
+ * convert floating to ascii.  ftoa returns an integer e such that
+ * f=g*10**e, with .1<=|g|<1 (e=0 when g==0) and puts an ascii
+ * representation of g in the buffer pointed to by bp.  bp[0] will
+ * be '+' or '-', and bp[1] to bp[NFTOA-2]
+ * will be appropriate digits of g. bp[NFTOA-1] will be '\0'
+ */
+int ftoa(double f, char *bp){
+	int e, e1, e2, i;
+	double digit, g, p;
+	if(f>=0) *bp++='+';
+	else{
+		f=-f;
+		*bp++='-';
+	}
+	/* find e such that f==0 or 1<=f*pow10(e)<10, and set f=f*pow10(e) */
+	if(f==0.) e=1;
+	else{
+		frexp(f, &e);
+		e=-e*30103/100000;
+		/* split in 2 pieces to guard against overflow in extreme cases */
+		e1=e/2;
+		e2=e-e1;
+		p=f*pow10(e2);
+		while((g=p*pow10(e1))<1.) e1++;
+		while((g=p*pow10(e1))>=10.) --e1;
+		e=e1+e2;
+		f=g;
+	}
+	for(i=0;i!=NDIG;i++){
+		f=modf(f, &digit)*10.;
+		*bp++=digit+'0';
+	}
+	*bp='\0';
+	return 1-e;
+}