Does a lot of work towards the PIT

Added a math library, with clamp and POW.
added printf support for printing doubles
added a few helper functions in PIT for calcaulting the time in seconds of a clock cycle based on divisor

libc/include/math.h

@@ -0,0 +1,13 @@
+#include <stdint.h>
+
+#ifndef MATH_H
+#define MATH_H
+
+int pow(int base, int exp);
+
+uint8_t clamp_u8(uint8_t val, uint8_t min, uint8_t max);
+uint16_t clamp_u16(uint16_t val, uint16_t min, uint16_t max);
+uint32_t clamp_u32(uint32_t val, uint32_t min, uint32_t max);
+uint64_t clamp_u64(uint64_t val, uint64_t min, uint64_t max);
+
+#endif

libc/include/stdlib.h

@@ -20,5 +20,7 @@ char* u8toa(uint8_t num, char* buf, int base);
 char* itoa(int num, char* buf, int base);
 char* utoa(unsigned int num, char* buf, int base);
 
+char* dtoa(double n, char* buf, int afterpoint);
+
 
 #endif

libc/math/clamp.c

@@ -0,0 +1,39 @@
+#include <stdint.h>
+#include <math.h>
+
+uint8_t clamp_u8(uint8_t val, uint8_t min, uint8_t max)
+{
+	if (val > max)
+		return max;
+	if (val < min)
+		return min;
+	return val;
+}
+
+uint16_t clamp_u16(uint16_t val, uint16_t min, uint16_t max)
+{
+	if (val > max)
+		return max;
+	if (val < min)
+		return min;
+	return val;
+}
+
+uint32_t clamp_u32(uint32_t val, uint32_t min, uint32_t max)
+{
+	if (val > max)
+		return max;
+	if (val < min)
+		return min;
+	return val;
+
+}
+
+uint64_t clamp_u64(uint64_t val, uint64_t min, uint64_t max)
+{	
+	if (val > max)
+		return max;
+	if (val < min)
+		return min;
+	return val;
+}

libc/math/pow.c

@@ -0,0 +1,9 @@
+#include <math.h>
+
+int pow(int base, int exp)
+{
+	int res = base;
+	for (int i = 0; i < exp; i++)
+		res *= base;
+	return res;
+}

libc/stdio/printf.c

@@ -77,6 +77,18 @@ int printf(const char* restrict format, ...) {
 			if (!print(buffer, len))
 				return -1;
 			written += len;
+		} else if (*format == 'f') {
+			format++;
+			double d = (double) va_arg(parameters, double);
+			dtoa(d, buffer, 5);
+			size_t len = strlen(buffer);
+			if (maxrem < len) {
+				// TODO
+				return -1;
+			}
+			if (!print(buffer, len))
+				return -1;
+			written += len;
 		} else if (*format == 'u') {
 			format++;
 			unsigned int i = (unsigned int) va_arg(parameters, unsigned int);

libc/stdlib/itoa.c

@@ -1,5 +1,7 @@
 #include <stdbool.h>
 #include <stdint.h>
+#include <string.h>
+#include <math.h>
 
 static void reverse(char* buf, int len)
 {
@@ -273,3 +275,35 @@ char* utoa(unsigned int num, char* buf, int base)
 	reverse(buf, i); // reverse, since we did it backwards!
 	return buf;
 }
+
+static int dbl_to_str(int x, char* buf, int d)
+{
+	int i = 0;
+	while (x) {
+		buf[i++] = (x % 10) + '0';
+		x = x / 10;
+	}
+
+	while (i < d)
+		buf[i++] = '0';
+
+	reverse(buf, i);
+	buf[i] = '\0';
+	return i;
+}
+
+char* dtoa(double n, char* buf, int afterpoint)
+{
+	int whole = (int) n;
+	
+	double decimals = n - (double) whole;
+
+	int i = dbl_to_str(whole, buf, 0);
+	if (afterpoint != 0) {
+		buf[i] = '.'; // add the decimal
+
+		decimals = decimals * pow(10, afterpoint);
+		dbl_to_str((int) decimals, buf + i + 1, afterpoint + 1);
+	}
+	return buf;
+}