diff options
| -rw-r--r-- | kernel/uart.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/kernel/uart.c b/kernel/uart.c index d586ea4..3c1dc34 100644 --- a/kernel/uart.c +++ b/kernel/uart.c @@ -42,8 +42,8 @@ struct spinlock uart_tx_lock; #define UART_TX_BUF_SIZE 32 char uart_tx_buf[UART_TX_BUF_SIZE]; -int uart_tx_w; // write next to uart_tx_buf[uart_tx_w++] -int uart_tx_r; // read next from uart_tx_buf[uar_tx_r++] +uint64 uart_tx_w; // write next to uart_tx_buf[uart_tx_w % UART_TX_BUF_SIZE] +uint64 uart_tx_r; // read next from uart_tx_buf[uar_tx_r % UART_TX_BUF_SIZE] extern volatile int panicked; // from printf.c @@ -94,13 +94,13 @@ uartputc(int c) } while(1){ - if(((uart_tx_w + 1) % UART_TX_BUF_SIZE) == uart_tx_r){ + if(uart_tx_w == uart_tx_r + UART_TX_BUF_SIZE){ // buffer is full. // wait for uartstart() to open up space in the buffer. sleep(&uart_tx_r, &uart_tx_lock); } else { - uart_tx_buf[uart_tx_w] = c; - uart_tx_w = (uart_tx_w + 1) % UART_TX_BUF_SIZE; + uart_tx_buf[uart_tx_w % UART_TX_BUF_SIZE] = c; + uart_tx_w += 1; uartstart(); release(&uart_tx_lock); return; @@ -150,8 +150,8 @@ uartstart() return; } - int c = uart_tx_buf[uart_tx_r]; - uart_tx_r = (uart_tx_r + 1) % UART_TX_BUF_SIZE; + int c = uart_tx_buf[uart_tx_r % UART_TX_BUF_SIZE]; + uart_tx_r += 1; // maybe uartputc() is waiting for space in the buffer. wakeup(&uart_tx_r); |