Integer sine approximation

sine.c

#include <stdint.h>

#define table_length_bits		5
//full_table_index_type have to be at least table_length_bits + 2
#define full_table_index_type	uint_least8_t
//table_index_type have to be at least table_length_bits
#define table_index_type		uint_least8_t

#define storage_bits			15
//Output will be +/- storage_bits so 15 bits storage will be 16 bit output
#define storage_type			int16_t

#define index_bits				16
#define index_type				uint_least16_t

#define top(n)					((1 << (n)) - 1)

#define inflation_bits 			(index_bits - table_length_bits)
#define full_inflation_bits 	(index_bits - table_length_bits - 2)
//fraction_type have to be at least full_inflation_bits
#define fraction_type			uint_least16_t

#define quarter_bits			(index_bits - 2)

#define ti_top					top(table_length_bits)
#define fib_top					top(full_inflation_bits)

const storage_type table[1 << table_length_bits] = {0, 1618, 3232, 4837, 6431, 8007, 9564, 11095, 12598, 14069, 15504, 16899, 18250, 19555, 20809, 22010, 23155, 24240, 25263, 26221, 27112, 27933, 28682, 29358, 29959, 30482, 30927, 31293, 31579, 31783, 31906, 31947};

int16_t get_sine(index_type p) {
	full_table_index_type fip = p >> full_inflation_bits;
	table_index_type sp = fip & ti_top;
	uint_least8_t q = p >> quarter_bits;
	fraction_type f = (p - (sp << full_inflation_bits)) & fib_top;

	storage_type r1, r2;
	if ((q & 0x1) == 0) {
		r1 = table[sp];
		if (sp == ti_top) {
			r2 = r1;
		} else {
			r2 = table[sp + 1];
		}
	} else {
		r2 = table[ti_top - sp];
		if (sp == 0) {
			r1 = r2;
		} else {
			r1 = table[ti_top - sp + 1];
		}
	}

	if (q & 0x2) {
		return ((r1 - r2) >> full_inflation_bits) * f - r1;
	} else {
		return ((r2 - r1) >> full_inflation_bits) * f + r1;
	}
	
}