#include "usart.h"
#include "os/delay.h"
#include <stddef.h>
#include <stdint.h>
#define USART_SR_TXE (1 << 7)

typedef struct uart_s {
    uint32_t USART_SR;
    uint32_t USART_DR;
    uint32_t USART_BRR;
    uint32_t USART_CR1;
    uint32_t USART_CR2;
    uint32_t USART_CR3;
    uint32_t USART_GTPR;
} uart_c;

volatile uart_c *const USART1 = (uart_c *)0x40011000;

static uint32_t usart_tx_ready(void) {
    return (USART1->USART_SR & USART_SR_TXE) >> 7;
}

uint32_t usart_tx_write(const uint8_t *data_bytes, uint32_t n_bytes) {
    if (data_bytes == NULL) return USART_TX_ERROR;

    for (int i = 0; i < n_bytes; i++) {
        unsigned int timeout = TIMEOUT;
        while (!usart_tx_ready()) {
            delay_ms(1);
            timeout--;
            if (timeout == 0) return USART_TX_BUSY;
        }

        USART1->USART_DR = *data_bytes;

        data_bytes++;
    }
    return USART_TX_COMPLETE;
}

uint32_t usart_tx_write_string(const uint8_t *data_bytes) {
    if (data_bytes == NULL) return USART_TX_ERROR;

    while (*data_bytes != '\0') {
        unsigned int timeout = TIMEOUT;
        while (!usart_tx_ready()) {
            delay_ms(1);
            timeout--;
            if (timeout == 0) return USART_TX_BUSY;
        }

        USART1->USART_DR = *data_bytes;

        data_bytes++;
    }
    return USART_TX_COMPLETE;
}