test_tms34020_setcdp.c

/* compile with gcc -lm -march=native test_tms34020_setcdp.c */
#include <stdint.h>
#include <stdio.h>
#include <math.h>

uint32_t setcdp(uint32_t dptch) {
	uint32_t m_convdp;
	// Check whether we're dealing with an even number
	if ((dptch & 1) == 0) {
		switch(__builtin_popcount(dptch))
		{
			// .. only single bit set, pitch is power of two!
			case 1:
			{
				uint32_t val = log2(dptch);
				m_convdp = ~val & 0x1f;
				// printf("case: power of two: input: %x, ouput: %x\t", dptch, m_convdp);
				return m_convdp;
			}
			// .. two bits, we can decompose it to sum of two power of two numbers
			case 2:
			{
				uint8_t v1 = __builtin_ffs(dptch) - 1;
				uint8_t v2 = __builtin_ffs(dptch & ~(1 << v1)) - 1;

				v1 = ~v1 & 0x1f;
				v2 = ~v2 & 0x1f;

				m_convdp = v2 + (v1 << 8);
				// printf("case: two powers of two: input: %x, ouput: %x\t", dptch, m_convdp);
				return m_convdp;
			}
		}
	}
	// Default to arbitrary number, setting pitch to 0
	m_convdp = 0;
	// printf("case: arbitrary: input: %x, ouput: %x\t", dptch, m_convdp);
    	return m_convdp;
}

int main() {
	uint32_t test_vectors[4][2] = {
		{0x1000,	0x13},
		{0x400,		0x15},
		{0x1400,	0x1513},
		{0x19,		0x0},
	};

	for (int i = 0; i < sizeof(test_vectors) / ( 2 * sizeof(uint32_t)); i++) {
		uint32_t result = setcdp(test_vectors[i][0]);
		printf("IN: %x: OUT: %x\t-\t", test_vectors[i][0], result);
		if (result != test_vectors[i][1]) {
			printf("FAIL!\n");
		} else {
			printf("OK!\n");
		}
	}

}