Add incredibly bad atof

apps/julia.c

@@ -214,7 +214,6 @@ int main(int argc, char * argv[]) {
 				case 'n':
 					no_repeat = 1;
 					break;
-#if 0
 				case 'i':
 					initer = atof(optarg);
 					break;
@@ -230,7 +229,6 @@ int main(int argc, char * argv[]) {
 				case 'C':
 					cony = atof(optarg);
 					break;
-#endif
 				case 'W':
 					width = atoi(optarg);
 					break;

base/usr/include/stdlib.h

@@ -19,4 +19,6 @@ extern int abs(int j);
 extern int putenv(char * name);
 extern int setenv(const char *name, const char *value, int overwrite);
 
+extern double atof(const char * nptr);
+
 #define NULL 0

libc/stdlib/atof.c

@@ -0,0 +1,41 @@
+/* Really bad atof */
+
+#include <stdlib.h>
+
+double atof(const char * nptr) {
+	int sign = 1;
+	if (*nptr == '-') {
+		sign = -1;
+		nptr++;
+	}
+
+	long long decimal_part = 0;
+
+	while (*nptr && *nptr != '.') {
+		if (*nptr < '0' || *nptr > '9') {
+			return 0.0;
+		}
+		decimal_part *= 10LL;
+		decimal_part += (long long)(*nptr - '0');
+		nptr++;
+	}
+
+	double sub_part = 0;
+	double multiplier = 0.1;
+
+	if (*nptr == '.') {
+		nptr++;
+
+		while (*nptr) {
+			if (*nptr < '0' || *nptr > '9') {
+				return ((double)decimal_part) * (double)(sign);
+			}
+
+			sub_part += multiplier * (*nptr - '0');
+			multiplier *= 0.1;
+			nptr++;
+		}
+	}
+
+	return ((double)decimal_part + sub_part) * (double)(sign);
+}