util.c

#include "types.h"
#include "util.h"

u32 rnd(void) {
  x1 = x1 * c1 + a1;
  x2 = x2 * c2 + a2;
  return (x1>>16) | (x2>>16);
}


u16 rotl(u16 value, u16 shift) {
    return (value << shift) | (value >> (16 - shift));
}

// http://www.jb.man.ac.uk/~slowe/cpp/itoa.html
// http://embeddedgurus.com/stack-overflow/2009/06/division-of-integers-by-constants/
// http://codereview.blogspot.com/2009/06/division-of-integers-by-constants.html
// http://homepage.cs.uiowa.edu/~jones/bcd/divide.html
/**
	 * C++ version 0.4 char* style "itoa":
	 * Written by Lukás Chmela
	 * Released under GPLv3.
	 */
char* itoa(int value, char* result, int base) {
	// check that the base if valid
	// removed for optimization
	// if (base < 2 || base > 36) { *result = '\0'; return result; }

	char* ptr = result, *ptr1 = result, tmp_char;
	int tmp_value;
	uint8_t inv = 0;

	// add: opt crashes on negatives
	if(value<0) {
		value = -value;
		inv++;
	}

	do {
		tmp_value = value;
		// opt-hack for base 10 assumed
		// value = (((uint16_t)value * (uint16_t)0xCD) >> 8) >> 3;
		value = (((uint32_t)value * (uint32_t)0xCCCD) >> 16) >> 3;
		// value /= base;
		*ptr++ = "zyxwvutsrqponmlkjihgfedcba9876543210123456789abcdefghijklmnopqrstuvwxyz" [35 + (tmp_value - value * base)];
	} while ( value );

	// Apply negative sign
	if(inv) *ptr++ = '-';
	*ptr-- = '\0';
	while(ptr1 < ptr) {
		tmp_char = *ptr;
		*ptr--= *ptr1;
		*ptr1++ = tmp_char;
	}
	return result;
}

u32 uclip(u32 value, u32 low, u32 high) {
	if (value < low) return low;
	if (value > high)	return high;
	return value;
}

s32 sclip(s32 value, s32 low, s32 high) {
	if (value < low) return low;
	if (value > high) return high;
	return value;
}