waves.h

#pragma once
 
#include "util/lookuptables/lookuptables.h"
 
#define CONG (jcong = 69069 * jcong + 1234567)
 
extern uint32_t z, w, jcong;
 
/* Basic waveform generation functions.
 *
 * Extracted from functions.h.
 */
 
// input must not have any extra bits set than numBitsInInput specifies
[[gnu::always_inline]] inline int32_t interpolateTableSigned(uint32_t input, int32_t numBitsInInput,
                                                             const int16_t* table, int32_t numBitsInTableSize = 8) {
    int32_t whichValue = input >> (numBitsInInput - numBitsInTableSize);
    int32_t rshiftAmount = numBitsInInput - 16 - numBitsInTableSize;
    uint32_t rshifted;
    if (rshiftAmount >= 0)
        rshifted = input >> rshiftAmount;
    else
        rshifted = input << (-rshiftAmount);
    int32_t strength2 = rshifted & 65535;
    int32_t strength1 = 65536 - strength2;
    return (int32_t)table[whichValue] * strength1 + (int32_t)table[whichValue + 1] * strength2;
}
 
[[gnu::always_inline]] inline int32_t getSine(uint32_t phase, uint8_t numBitsInInput = 32) {
    return interpolateTableSigned(phase, numBitsInInput, sineWaveSmall, 8);
}
 
[[gnu::always_inline]] inline int32_t getSquare(uint32_t phase, uint32_t phaseWidth = 2147483648u) {
    return ((phase >= phaseWidth) ? (-2147483648) : 2147483647);
}
 
[[gnu::always_inline]] inline int32_t getSquareSmall(uint32_t phase, uint32_t phaseWidth = 2147483648u) {
    return ((phase >= phaseWidth) ? (-1073741824) : 1073741823);
}
 
/* Should be faster, but isn't...
 * inline int32_t getTriangleSmall(int32_t phase) {
    int32_t multiplier = (phase >> 31) | 1;
    phase *= multiplier;
 */
 
[[gnu::always_inline]] inline int32_t getTriangleSmall(uint32_t phase) {
    if (phase >= 2147483648u)
        phase = -phase;
    return phase - 1073741824;
}
 
[[gnu::always_inline]] inline int32_t getTriangle(uint32_t phase) {
    int32_t slope = 2;
    int32_t offset = 0x80000000u;
    if (phase >= 0x80000000u) {
        slope = -2;
        offset = 0x80000000u - 1;
    }
    return slope * phase + offset;
}