#define _CRT_SECURE_NO_DEPRECATE
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>

typedef struct
{
    int autoreload;
    int prescaler;
    float realfreq;
} timer_config_t;

bool compute_timer_parameter(timer_config_t* config, int timer_in_clk /*mhz*/, int infreq /*hz*/)
{
    float psc_x_arr =(float) timer_in_clk * 1000 /*定时器模块时钟*/ * 1000 / infreq;
    uint32_t psc = 0;
    uint32_t arr = 65534;
    for (; arr > 2; arr--)
    {
        psc =(uint32_t)( psc_x_arr / arr);
        if (psc >= 1)
        {
            uint32_t tmparr = psc_x_arr / psc;
            if (tmparr >= 65534)
                continue;
            break;
        }
    }
    if (psc == 0)
        return false;
    if (arr <= 3)
        return false; //定时器一周期的分辨率太小了
    arr = psc_x_arr / psc;

    int psc_x_arr_real = arr * psc;
    float realfreq = timer_in_clk * 1000.0 /*定时器模块时钟*/ * 1000 / psc_x_arr_real;

    arr = arr - 1;
    psc = psc - 1;

    config->autoreload = arr;
    config->prescaler = psc;
    config->realfreq = realfreq;
    // config->compare = arr / 2;
    return false;
}

void dumpconfig_info(timer_config_t* config)
{
    printf("* freq      : %f \n", config->realfreq);
    printf("* prescaler : %d \n", config->prescaler);
    printf("* autoreload: %d \n", config->autoreload);
}

int main(int argc, char const* argv[])
{
    if (argc != 3)
    {
        printf("%s timerInClk mhz expect_freq khz\n", argv[0]);
        return -1;
    }

    float expect_freq = 0;
    float timerInClk = 0;
   
    sscanf(argv[1], "%f", &timerInClk);
    sscanf(argv[2], "%f", &expect_freq);

    printf("******************************************************\n");
    printf("* author: zhaohe                                     *\n");
    printf("* e-mail: h_zhaohe@163.com                           *\n");
    printf("******************************************************\n");
    printf("*\n");
    printf("* timerInClk  : %f mhz\n", timerInClk);
    printf("* expect freq: %f khz\n", expect_freq);
    printf("*\n");

    int32_t infreq = (int32_t)(expect_freq * 1000);
    timer_config_t timerconfig_apb2;

    compute_timer_parameter(&timerconfig_apb2, timerInClk, infreq);

    printf("******************************************************\n");
    printf("*\n");
    printf("* timer_module_clk: %f mhz\n", timerInClk);
    printf("* freq            : %f khz\n", timerconfig_apb2.realfreq / 1000.0);
    printf("* period          : %f ms\n", (1.0 / timerconfig_apb2.realfreq * 1000));
    printf("* prescaler       : %d \n", timerconfig_apb2.prescaler);
    printf("* autoreload      : %d \n", timerconfig_apb2.autoreload);
    printf("*\n");

    return 0;
}