Implement serial command parser with floating point support

src/common/parser.c

@@ -0,0 +1,72 @@
+#include "common.h"
+
+#include <stdlib.h>
+#include <ctype.h>
+#include <errno.h>
+
+#define CMD_MAX_LEN 128
+
+// TODO: Write documentation.
+// TODO: Implement start and stop commands.
+// TODO: Reset command buffer on timeout?
+
+static char cmdbuf[CMD_MAX_LEN + 1];
+static char *tail = cmdbuf + CMD_MAX_LEN - 1;
+static char *head = cmdbuf;
+
+static bool ParseLine(cmd_t *out);
+
+bool CMD_Parse(char ch, cmd_t *out)
+{
+	bool is_valid;
+
+	if (ch == '\n' || ch == '\r') {
+		is_valid = ParseLine(out);
+		tail = cmdbuf + CMD_MAX_LEN - 1; 
+		head = cmdbuf;
+		return is_valid;
+	}
+
+	if (head < tail) {
+		*head++ = ch;
+		*head = '\0';
+	}
+
+	return false;
+}
+
+static bool ParseLine(cmd_t *out)
+{
+	head = cmdbuf;
+
+	// Command SET <float> <float>
+	if (tolower(head[0] == 's')) {
+		if ((tolower(head[1]) != 'e') ||
+		    (tolower(head[2]) != 't')) {
+			return false;
+		}
+
+		out->type = T_SET;
+		head += 3;
+
+		// Parse <float> arguments
+		for (int i = 0; i < 2; i++) {
+			errno = 0;
+
+			// Try converting string to floating point
+			// Skips whitespace and moves tail pointer
+			out->args[i] = (float) strtod(head, &tail);
+
+			if ((errno == ERANGE) ||
+			    (out->args[i] == 0 && head == tail)) {
+				return false; // Conversion failed
+			}
+
+			head = tail;
+		}
+
+		return true;
+	}
+
+	return false;
+}

src/common/parser.h

@@ -0,0 +1,18 @@
+#ifndef MAD_CORE_COMMON_PARSER
+#define MAD_CORE_COMMON_PARSER
+
+#include "common/types.h"
+
+// Command types
+#define T_SET  0
+
+struct cmd_s {
+	int    type;
+	float  args[2];
+};
+
+typedef struct cmd_s cmd_t;
+
+bool CMD_Parse(char ch, cmd_t *out);
+
+#endif // MAD_CORE_COMMON_PARSER