diff options
| -rw-r--r-- | common/uart_buffering.c | 122 |
1 files changed, 108 insertions, 14 deletions
diff --git a/common/uart_buffering.c b/common/uart_buffering.c index 030626f860..6b43041ce3 100644 --- a/common/uart_buffering.c +++ b/common/uart_buffering.c @@ -21,6 +21,9 @@ #define RX_BUF_NEXT(i) (((i) + 1) & (RX_BUF_SIZE - 1)) #define RX_BUF_PREV(i) (((i) - 1) & (RX_BUF_SIZE - 1)) +/* Macro to calculate difference of pointers in the circular receive buffers */ +#define RX_BUF_DIFF(i, j) (((i) - (j)) & (RX_BUF_SIZE - 1)) + /* Transmit and receive buffers */ static volatile char tx_buf[TX_BUF_SIZE]; static volatile int tx_buf_head; @@ -28,8 +31,10 @@ static volatile int tx_buf_tail; static volatile char rx_buf[RX_BUF_SIZE]; static volatile int rx_buf_head; static volatile int rx_buf_tail; +static volatile int rx_buf_ptr; static int last_rx_was_cr; static int in_escape; +static char esc_seq_char; static int console_mode = 1; @@ -57,6 +62,88 @@ static int __tx_char(int c) return 0; } +static void move_rx_ptr_fwd(void) +{ + if (rx_buf_ptr != rx_buf_head) { + rx_buf_ptr = RX_BUF_NEXT(rx_buf_ptr); + uart_write_char(0x1B); + uart_write_char('['); + uart_write_char('1'); + uart_write_char('C'); + } +} + +static void move_rx_ptr_bwd(void) +{ + if (rx_buf_ptr != rx_buf_tail) { + rx_buf_ptr = RX_BUF_PREV(rx_buf_ptr); + uart_write_char(0x1B); + uart_write_char('['); + uart_write_char('1'); + uart_write_char('D'); + } +} + +static void move_cursor_back(int dist) +{ + while (dist--) + uart_write_char('\b'); +} + +static void handle_backspace(void) +{ + if (rx_buf_ptr != rx_buf_tail) { + /* Move texts after cursor and also update rx buffer. */ + int ptr = rx_buf_ptr; + while (ptr != rx_buf_head) { + uart_write_char(rx_buf[ptr]); + rx_buf[RX_BUF_PREV(ptr)] = rx_buf[ptr]; + ptr = RX_BUF_NEXT(ptr); + } + /* Space over last character and move cursor back to correct + * position. + */ + uart_write_char(' '); + move_cursor_back(RX_BUF_DIFF(ptr, rx_buf_ptr) + 1); + + rx_buf_head = RX_BUF_PREV(rx_buf_head); + rx_buf_ptr = RX_BUF_PREV(rx_buf_ptr); + } + else + /* Cursor moves pass the first character. Move it back. */ + uart_write_char(' '); +} + +static void insert_char(char c) +{ + int ptr; + + /* Move buffer ptr to the end if 'c' is new line */ + if (c == '\n') + rx_buf_ptr = rx_buf_head; + + /* Move text after cursor. */ + ptr = rx_buf_ptr; + while (ptr != rx_buf_head) { + uart_write_char(rx_buf[ptr]); + ptr = RX_BUF_NEXT(ptr); + } + /* Insert character to rx buffer and move cursor to correct + * position. + */ + while (ptr != rx_buf_ptr) { + rx_buf[ptr] = rx_buf[RX_BUF_PREV(ptr)]; + uart_write_char('\b'); + ptr = RX_BUF_PREV(ptr); + } + rx_buf[rx_buf_ptr] = c; + rx_buf_head = RX_BUF_NEXT(rx_buf_head); + rx_buf_ptr = RX_BUF_NEXT(rx_buf_ptr); + /* On overflow, discard oldest output */ + if (rx_buf_head == rx_buf_tail) + rx_buf_tail = RX_BUF_NEXT(rx_buf_tail); +} + /* Helper for UART processing */ void uart_process(void) { @@ -77,16 +164,32 @@ void uart_process(void) last_rx_was_cr = 0; } - /* Eat common terminal escape sequences (ESC [ ...). + /* Handle left and right key, and eat other terminal + * escape sequences (ESC [ ...). * Would be really cool if we used arrow keys to edit * command history, but for now it's sufficient just to * keep them from causing problems. */ if (c == 0x1B) { in_escape = 1; + esc_seq_char = c; continue; } else if (in_escape) { - if (isalpha(c) || c == '~') + if (esc_seq_char == 0x1B && c == '[') + esc_seq_char = '['; + else if (esc_seq_char == '[') { + if (c == 'D') /* Left key */ + move_rx_ptr_bwd(); + else if (c == 'C') /* Right key */ + move_rx_ptr_fwd(); + esc_seq_char = 0; + } + else + esc_seq_char = 0; + + if (isalpha(c) || c == '~') { + esc_seq_char = 0; in_escape = 0; + } continue; } @@ -100,22 +203,12 @@ void uart_process(void) /* Handle backspace if we can */ if (c == '\b') { - if (rx_buf_head != rx_buf_tail) { - /* Delete the previous character (and - * space over it on the output) */ - uart_write_char(' '); - uart_write_char('\b'); - rx_buf_head = RX_BUF_PREV(rx_buf_head); - } + handle_backspace(); continue; } } - rx_buf[rx_buf_head] = c; - rx_buf_head = RX_BUF_NEXT(rx_buf_head); - /* On overflow, discard oldest output */ - if (rx_buf_head == rx_buf_tail) - rx_buf_tail = RX_BUF_NEXT(rx_buf_tail); + insert_char(c); /* Call console callback on newline, if in console mode */ if (console_mode && c == '\n') @@ -416,6 +509,7 @@ int uart_gets(char *dest, int size) if (c == '\n') break; /* Stop on newline */ } + rx_buf_ptr = rx_buf_tail; /* Re-enable interrupts */ uart_enable_interrupt(); |