/* See LICENSE file for copyright and license details. */
#include "ramps.h"


/**
 * Test mapping function from [0, 1] float encoding value to [0, 2⁸ − 1] integer output value
 * 
 * @param   encoding  [0, 1] float encoding value
 * @return            [0, 2⁸ − 1] integer output value
 */
uint8_t
invert_ramps8(float encoding)
{
	double i_encoding = (double)(1.f - encoding);
	double f_output = (double)UINT8_MAX * i_encoding;
	uint8_t output = (uint8_t)f_output;
	if (i_encoding < (double)0.25f && output > UINT8_MAX / 2)
		output = 0;
	if (i_encoding > (double)0.75f && output < UINT8_MAX / 2)
		output = UINT8_MAX;
	return output;
}

/**
 * Test mapping function from [0, 1] float encoding value to [0, 2¹⁶ − 1] integer output value
 * 
 * @param   encoding  [0, 1] float encoding value
 * @return            [0, 2¹⁶ − 1] integer output value
 */
uint16_t
invert_ramps16(float encoding)
{
	double i_encoding = (double)(1.f - encoding);
	double f_output = (double)UINT16_MAX * i_encoding;
	uint16_t output = (uint16_t)f_output;
	if (i_encoding < (double)0.25f && output > UINT16_MAX / 2)
		output = 0;
	if (i_encoding > (double)0.75f && output < UINT16_MAX / 2)
		output = UINT16_MAX;
	return output;
}

/**
 * Test mapping function from [0, 1] float encoding value to [0, 2³² − 1] integer output value
 * 
 * @param   encoding  [0, 1] float encoding value
 * @return            [0, 2³² − 1] integer output value
 */
uint32_t
invert_ramps32(float encoding)
{
	double i_encoding = (double)(1.f - encoding);
	double f_output = (double)UINT32_MAX * i_encoding;
	uint32_t output = (uint32_t)f_output;
	if (i_encoding < (double)0.25f && output > UINT32_MAX / 2)
		output = 0;
	if (i_encoding > (double)0.75f && output < UINT32_MAX / 2)
		output = UINT32_MAX;
	return output;
}

/**
 * Test mapping function from [0, 1] float encoding value to [0, 2⁶⁴ − 1] integer output value
 * 
 * @param   encoding  [0, 1] float encoding value
 * @return            [0, 2⁶⁴ − 1] integer output value
 */
uint64_t
invert_ramps64(float encoding)
{
	double i_encoding = (double)(1.f - encoding);
	double f_output = (double)UINT64_MAX * i_encoding;
	uint64_t output = (uint64_t)f_output;
	if (i_encoding < (double)0.25f && output > UINT64_MAX / 2)
		output = 0;
	if (i_encoding > (double)0.75f && output < UINT64_MAX / 2)
		output = UINT64_MAX;
	return output;
}

/**
 * Test mapping function from [0, 1] float encoding value to [0, 1] float output value
 * 
 * @param   encoding  [0, 1] float encoding value
 * @return            [0, 1] float output value
 */
float
invert_rampsf(float encoding)
{
	return 1.f - encoding;
}

/**
 * Test mapping function from [0, 1] double precision float encoding
 * value to [0, 1] double precision float output value
 * 
 * @param   encoding  [0, 1] float encoding value
 * @return            [0, 1] float output value
 */
double
invert_rampsd(double encoding)
{
	return (double)1.f - encoding;
}