circuitpython/stmhal/readline.c

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#include <string.h>
#include <stm32f4xx_hal.h>
#include "misc.h"
#include "mpconfig.h"
#include "qstr.h"
#include "misc.h"
#include "obj.h"
#include "pybstdio.h"
#include "readline.h"
#include "usb.h"
#define READLINE_HIST_SIZE (8)
static const char *readline_hist[READLINE_HIST_SIZE] = {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL};
void readline_init(void) {
memset(readline_hist, 0, READLINE_HIST_SIZE * sizeof(const char*));
}
STATIC char *str_dup(const char *str) {
uint32_t len = strlen(str);
char *s2 = m_new(char, len + 1);
memcpy(s2, str, len);
s2[len] = 0;
return s2;
}
int readline(vstr_t *line, const char *prompt) {
stdout_tx_str(prompt);
int orig_line_len = line->len;
int escape_seq = 0;
int hist_cur = -1;
int cursor_pos = orig_line_len;
for (;;) {
int c = stdin_rx_chr();
int last_line_len = line->len;
int redraw_step_back = 0;
bool redraw_from_cursor = false;
int redraw_step_forward = 0;
if (escape_seq == 0) {
if (VCP_CHAR_CTRL_A <= c && c <= VCP_CHAR_CTRL_D && vstr_len(line) == orig_line_len) {
// control character with empty line
return c;
} else if (c == '\r') {
// newline
stdout_tx_str("\r\n");
if (line->len > orig_line_len && (readline_hist[0] == NULL || strcmp(readline_hist[0], line->buf + orig_line_len) != 0)) {
// a line which is not empty and different from the last one
// so update the history
for (int i = READLINE_HIST_SIZE - 1; i > 0; i--) {
readline_hist[i] = readline_hist[i - 1];
}
readline_hist[0] = str_dup(line->buf + orig_line_len);
}
return 0;
} else if (c == 27) {
// escape sequence
escape_seq = 1;
} else if (c == 127) {
// backspace
if (cursor_pos > orig_line_len) {
vstr_cut_out_bytes(line, cursor_pos - 1, 1);
// set redraw parameters
redraw_step_back = 1;
redraw_from_cursor = true;
}
} else if (32 <= c && c <= 126) {
// printable character
vstr_ins_char(line, cursor_pos, c);
// set redraw parameters
redraw_from_cursor = true;
redraw_step_forward = 1;
}
} else if (escape_seq == 1) {
if (c == '[') {
escape_seq = 2;
} else {
escape_seq = 0;
}
} else if (escape_seq == 2) {
escape_seq = 0;
if (c == 'A') {
// up arrow
if (hist_cur + 1 < READLINE_HIST_SIZE && readline_hist[hist_cur + 1] != NULL) {
// increase hist num
hist_cur += 1;
// set line to history
line->len = orig_line_len;
vstr_add_str(line, readline_hist[hist_cur]);
// set redraw parameters
redraw_step_back = cursor_pos - orig_line_len;
redraw_from_cursor = true;
redraw_step_forward = line->len - orig_line_len;
}
} else if (c == 'B') {
// down arrow
if (hist_cur >= 0) {
// decrease hist num
hist_cur -= 1;
// set line to history
vstr_cut_tail_bytes(line, line->len - orig_line_len);
if (hist_cur >= 0) {
vstr_add_str(line, readline_hist[hist_cur]);
}
// set redraw parameters
redraw_step_back = cursor_pos - orig_line_len;
redraw_from_cursor = true;
redraw_step_forward = line->len - orig_line_len;
}
} else if (c == 'C') {
// right arrow
if (cursor_pos < line->len) {
redraw_step_forward = 1;
}
} else if (c == 'D') {
// left arrow
if (cursor_pos > orig_line_len) {
redraw_step_back = 1;
}
}
} else {
escape_seq = 0;
}
// redraw command prompt, efficiently
if (redraw_step_back > 0) {
for (int i = 0; i < redraw_step_back; i++) {
stdout_tx_str("\b");
}
cursor_pos -= redraw_step_back;
}
if (redraw_from_cursor) {
if (line->len < last_line_len) {
// erase old chars
for (int i = cursor_pos; i < last_line_len; i++) {
stdout_tx_str(" ");
}
// step back
for (int i = cursor_pos; i < last_line_len; i++) {
stdout_tx_str("\b");
}
}
// draw new chars
stdout_tx_strn(line->buf + cursor_pos, line->len - cursor_pos);
// move cursor forward if needed (already moved forward by length of line, so move it back)
for (int i = cursor_pos + redraw_step_forward; i < line->len; i++) {
stdout_tx_str("\b");
}
cursor_pos += redraw_step_forward;
} else if (redraw_step_forward > 0) {
// draw over old chars to move cursor forwards
stdout_tx_strn(line->buf + cursor_pos, redraw_step_forward);
cursor_pos += redraw_step_forward;
}
HAL_Delay(1);
}
}