Used for audio processing or synthesis algorithms, where the normalized time is used to apply effects or transformations to an audio signal based on its position in time. Values returned: 0 to 1 from 0 to the number of points/samples/frames/etc.

index_time_x.m

const AVAudioFrameCount frame_count = ...;

typedef simd_double1 * normalized_time_ref[frame_count];
typeof(normalized_time_ref) normalized_time;
__block simd_double1 * normalized_time_ptr = &normalized_time;
AVAudioFrameCount frame = 0;
AVAudioFrameCount * frame_t = &frame;

const simd_double1 frame_index_offset = frame_count - 1.f;
for (*frame_t = 0; *frame_t < frame_count; *frame_t += 1) {
   simd_double1 time = ((*frame_t - 1.f) / (frame_index_offset - 1.f));
   *(normalized_time_ptr + *frame_t) = time;
}

for (*frame_t = *frame_t - 1; *frame_t > 0; *frame_t -= 1) {
   simd_double1 time = *(normalized_time_ptr + *frame_t);
}