rl_helper: implement a minimal line editing prompt

With this helper, we can replace fgets and printf, so we are able to do
editing line and command history.

3 files changed, 132 insertions, 1 deletions

diff --git a/Android.mk b/Android.mk
index c6aae80..7e5fe03 100644
--- a/Android.mk
+++ b/Android.mk
@@ -2,7 +2,7 @@ LOCAL_PATH:= $(call my-dir)
 
 include $(CLEAR_VARS)
 
-LOCAL_SRC_FILES := btctl.c util.c
+LOCAL_SRC_FILES := btctl.c util.c rl_helper.c
 LOCAL_SHARED_LIBRARIES := libhardware
 LOCAL_MODULE_TAGS := eng
 LOCAL_MODULE := btctl
diff --git a/rl_helper.c b/rl_helper.c
new file mode 100644
index 0000000..1e7c2ae
--- /dev/null
+++ b/rl_helper.c
@@ -0,0 +1,118 @@
+/*
+ * Line editing helper
+ *
+ * Copyright (C) 2013 Jefferson Delfes
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ */
+
+#include <ctype.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+#include <termios.h>
+#include "rl_helper.h"
+
+#define MAX_LINE_BUFFER 512
+
+typedef enum {
+    K_ESC       = 0x1b,
+    K_BACKSPACE = 0x7f,
+    /* user defined codes (used for escape sequences */
+    K_UP    = 0x100,
+    K_DOWN  = 0x101,
+    K_RIGHT = 0x102,
+    K_LEFT  = 0x103,
+} keys_t;
+
+line_process_callback line_cb;
+char lnbuf[MAX_LINE_BUFFER]; /* buffer for our line editing */
+size_t pos = 0;
+
+void rl_clear() {
+
+    memset(lnbuf, 0, sizeof(lnbuf));
+    pos = 0;
+}
+
+/* clear current line and returns to line begin */
+void rl_clear_line() {
+
+    printf("\x1b[2K\r");
+}
+
+void rl_reprint_prompt() {
+
+    rl_clear_line();
+    printf("> %s", lnbuf);
+    fflush(stdout);
+}
+
+void rl_init(line_process_callback cb) {
+    struct termios settings;
+
+    /* disable echo */
+    tcgetattr(0, &settings); /* read settings from stdin (0) */
+    settings.c_lflag &= ~(ICANON | ECHO); /* disable canonical and echo flags */
+    tcsetattr(0, TCSANOW, &settings); /* store new settings */
+
+    rl_clear();
+    line_cb = cb;
+}
+
+void rl_quit() {
+
+    rl_clear();
+    rl_clear_line();
+}
+
+void rl_feed(int c) {
+
+    switch (c) {
+        case '\r':
+        case '\n':
+            putchar('\n');
+            line_cb(lnbuf);
+            rl_clear();
+            rl_reprint_prompt();
+            break;
+        case K_ESC:
+            break;
+        case K_BACKSPACE:
+            if (pos > 0) {
+                memmove(lnbuf + pos - 1, lnbuf + pos, sizeof(lnbuf) - pos);
+                rl_reprint_prompt();
+                pos--;
+            }
+            break;
+        case K_UP:
+        case K_DOWN:
+            /* history handle */
+            break;
+        case K_RIGHT:
+        case K_LEFT:
+            break;
+        default:
+            if (isprint(c)) {
+                if (pos < MAX_LINE_BUFFER) {
+                    lnbuf[pos++] = c;
+                    rl_reprint_prompt();
+                }
+            } else
+                printf(" %x ", c);
+            break;
+    }
+}
diff --git a/rl_helper.h b/rl_helper.h
new file mode 100644
index 0000000..3da3406
--- /dev/null
+++ b/rl_helper.h
@@ -0,0 +1,13 @@
+#ifndef __RL_HELPER_H__
+#define __RL_HELPER_H__
+
+typedef void (*line_process_callback)(char *line);
+
+/* initializes buffers and set line process callback */
+void rl_init(line_process_callback cb);
+/* close resources */
+void rl_quit();
+/* add char to line buffer */
+void rl_feed(int c);
+
+#endif // __RL_HELPER_H__