#include "fft_plan.hpp"
#include <cstring>

namespace fft {

void init_plan(FFTPlan* plan, uint32_t log2N) {
    plan->log2N = log2N;
    plan->N = 1U << log2N;
    plan->stage_count = 0;
    plan->bit_reverse = 0;
    plan->xor_mask = 0;
    
    uint32_t n = plan->N;
    while (n > 1) {
        if (n % 8 == 0 && log2N >= 3) {
            plan->stages[plan->stage_count].radix = 8;
            plan->stages[plan->stage_count].group_size = n / 8;
            plan->stages[plan->stage_count].groups = 8;
            plan->stage_count++;
            n /= 8;
        } else if (n % 4 == 0 && log2N >= 2) {
            plan->stages[plan->stage_count].radix = 4;
            plan->stages[plan->stage_count].group_size = n / 4;
            plan->stages[plan->stage_count].groups = 4;
            plan->stage_count++;
            n /= 4;
        } else if (n % 2 == 0) {
            plan->stages[plan->stage_count].radix = 2;
            plan->stages[plan->stage_count].group_size = n / 2;
            plan->stages[plan->stage_count].groups = 2;
            plan->stage_count++;
            n /= 2;
        }
    }
}

}