#include "retarget.h"

#include <stdio.h>

#include "app_config.h"
#include "stm32g474xx.h"

#if defined(__ARMCC_VERSION) && (__ARMCC_VERSION < 6000000)
#pragma import(__use_no_semihosting)

struct __FILE
{
    int handle;
};
#elif defined(__ARMCC_VERSION)
__asm(".global __use_no_semihosting\n");
#endif

FILE __stdout;
FILE __stdin;

static void gpio_pc10_pc11_to_usart3(void)
{
    RCC->AHB2ENR |= RCC_AHB2ENR_GPIOCEN;
    (void)RCC->AHB2ENR;

    /* PC10 = USART3_TX, PC11 = USART3_RX, AF7: ST-LINK VCP on CN3. */
    GPIOC->MODER &= ~((3UL << (10U * 2U)) | (3UL << (11U * 2U)));
    GPIOC->MODER |=  ((2UL << (10U * 2U)) | (2UL << (11U * 2U)));

    GPIOC->OTYPER &= ~((1UL << 10U) | (1UL << 11U));
    GPIOC->OSPEEDR |= ((3UL << (10U * 2U)) | (3UL << (11U * 2U)));
    GPIOC->PUPDR &= ~((3UL << (10U * 2U)) | (3UL << (11U * 2U)));

    GPIOC->AFR[1] &= ~((0xFUL << ((10U - 8U) * 4U)) | (0xFUL << ((11U - 8U) * 4U)));
    GPIOC->AFR[1] |=  ((7UL   << ((10U - 8U) * 4U)) | (7UL   << ((11U - 8U) * 4U)));
}

void Retarget_Init(uint32_t baudrate)
{
    gpio_pc10_pc11_to_usart3();

    RCC->APB1ENR1 |= RCC_APB1ENR1_USART3EN;
    (void)RCC->APB1ENR1;

    USART3->CR1 = 0U;
    USART3->CR2 = 0U;
    USART3->CR3 = 0U;

    /* APB1 is not prescaled; use the clock that really started. */
    USART3->BRR = (SystemCoreClock + (baudrate / 2U)) / baudrate;
    USART3->CR1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_UE;
}

void Retarget_PutChar(char ch)
{
    while ((USART3->ISR & USART_ISR_TXE_TXFNF) == 0U)
    {
        __NOP();
    }
    USART3->TDR = (uint8_t)ch;
}

int fputc(int ch, FILE *f)
{
    (void)f;

    if (ch == '\n')
    {
        Retarget_PutChar('\r');
    }

    Retarget_PutChar((char)ch);
    return ch;
}

int fgetc(FILE *f)
{
    (void)f;

    while ((USART3->ISR & USART_ISR_RXNE_RXFNE) == 0U)
    {
        __NOP();
    }

    return (int)(USART3->RDR & 0xFFU);
}

void _ttywrch(int ch)
{
    Retarget_PutChar((char)ch);
}

void _sys_exit(int return_code)
{
    (void)return_code;
    while (1)
    {
        __NOP();
    }
}