feature: add debug_plugin for development debugging

src/hexdump/hexdump.cpp

@@ -0,0 +1,37 @@
+#include "hexdump.h"
+
+void hexdump_to_fd(int fd, const char *data, uint16_t len)
+{
+    uint16_t i = 0;
+    uint16_t used = 0;
+    uint16_t offset = 0;
+
+#define LINE_LEN 80
+    char line[LINE_LEN]; /* space needed 8+16*3+3+16 == 75 */
+
+    dprintf(fd, "dump data at [%p], len=%u\n", data, len);
+    while (offset < len)
+    {
+        /* format the line in the buffer, then use printf to usedput to screen */
+        used = snprintf(line, LINE_LEN, "%08X:", offset);
+        for (i = 0; ((offset + i) < len) && (i < 16); i++)
+        {
+            used += snprintf(line + used, LINE_LEN - used, " %02X", (data[offset + i] & 0xff));
+        }
+        for (; i <= 16; i++)
+        {
+            used += snprintf(line + used, LINE_LEN - used, " | ");
+        }
+        for (i = 0; (offset < len) && (i < 16); i++, offset++)
+        {
+            unsigned char c = data[offset];
+            if ((c < ' ') || (c > '~'))
+            {
+                c = '.';
+            }
+            used += snprintf(line + used, LINE_LEN - used, "%c", c);
+        }
+        dprintf(fd, "%s\n", line);
+    }
+    dprintf(fd, "\n");
+}