Add first structure and start work on format specifier parser

src/simple-printf.c

@@ -0,0 +1,134 @@
+#include <simple-printf/simple-printf.h>
+#include <stddef.h>
+#include <stdbool.h>
+
+enum format_specifier_type {
+	FMT_INVALID = 0,
+	FMT_INTEGER,
+	FMT_UNSIGNED,
+	FMT_STRING,
+	FMT_HEXUINT_CAPITALIZED,
+	FMT_HEXUNIT,
+	FMT_CHAR,
+	FMT_SIZE,
+	FMT_PERCENT,
+};
+
+struct format_specifier {
+	enum format_specifier_type specifier;
+	size_t length; /**< @brief lenght of formatted output.*/
+	bool zero_pad; 
+	size_t length_of_provided_specifier;
+};
+
+static void parse_format_specifier(const char *start, struct format_specifier *result)
+{
+	size_t fmt_len = 1ull;
+	bool keep_parsing = true;
+	bool is_in_number = false;
+	const char *number;
+	size_t num_len = 0;
+	
+	result->specifier = FMT_INVALID;
+	result->zero_pad = 0;
+	result->length_of_provided_specifier = 0;
+	result->length = 0;
+	if (!start)
+		return;
+
+	/* Check if specifier starts with % */
+	if (*start != '%')
+		return;
+
+	start++;
+	while (keep_parsing) {
+		/* Parse the format specifier*/
+		switch (*start) {
+		case '0':
+			if (fmt_len == 1) {
+				result->zero_pad = 1;
+				break;
+			} 
+			/* Fallthru */		
+		case '1':
+		case '2':
+		case '3':
+		case '4':
+		case '5':
+		case '6':
+		case '7':
+		case '8':
+		case '9':
+			/* Number */
+			if (!is_in_number) {
+				/* Start of number */
+				is_in_number = true;
+				number = start;
+				num_len = 0;
+			} else {
+				/* Continue parsing number */
+				num_len++;
+			}
+			break;
+		case 'c':
+			result->specifier = FMT_CHAR;
+			keep_parsing = false;
+			break;
+		case 'z':
+			result->specifier = FMT_SIZE;
+			keep_parsing = false;
+			break;
+		case 'x':
+			result->specifier = FMT_HEXUNIT;
+			keep_parsing = false;
+			break;
+		case 'X':
+			result->specifier = FMT_HEXUINT_CAPITALIZED;
+			keep_parsing = false;
+			break;
+		case 's':
+			result->specifier = FMT_STRING;
+			keep_parsing = false;
+			break;
+		case 'u':
+			result->specifier = FMT_UNSIGNED;
+			keep_parsing = false;
+			break;
+		case 'i': /* Falltrhu */
+		case 'd':
+			result->specifier = FMT_INTEGER;
+			keep_parsing = false;
+			break;
+		case '%':
+			if (fmt_len == 1) {
+				result->specifier = FMT_PERCENT;
+			}
+			keep_parsing = false;
+		default:
+			/* Unrecognized stuff. Abort */
+			keep_parsing = false;
+			break;
+		}
+
+		if (keep_parsing == false) {
+			/* End reached. Check the number */
+			
+		}
+
+		start++;
+		fmt_len++;
+	}
+}
+
+int simple_snprintf(char *dest, size_t dest_size, const char *fmt, ...)
+{
+	int ret = -1;
+	
+	if (!dest || !dest_size || !fmt) {
+		/* Parameter error */
+		return -1000;
+	}
+
+	return ret;
+}
+