Write vsnprintf() implementation

2025-03-18 17:41:16 +01:00
parent 8674d32f77
commit 244b83d370
7 changed files with 138 additions and 27 deletions
@@ -0,0 +1,93 @@
+#include <kernel.h>
+#include <vsnprintf.h>
+
+int pf_isdigit(char c) {
+	if (c >= '0' && c <= '9') return 1;
+	return 0;
+}
+
+char* pf_itoa(uint32_t num, uint8_t base) {
+	static char buf[32];
+	
+	if (base == 0 || base > 16) return NULL;
+	
+	if (num == 0) {
+		buf[0] = '0';
+		buf[1] = '\0';
+		return &buf[0];
+	}
+
+	int i;
+	for (i = 30; num && i; i--, num /= base) {
+		buf[i] = "0123456789abcdef"[num % base];	
+	}
+	
+	return &buf[i + 1];
+}
+
+char* pf_ftoa(float f) {
+	return NULL;
+}
+
+int vsnprintf(char* buf, size_t len, char* fmt, va_list args) {
+	size_t i = 0;
+
+	while (*fmt != '\0' && i < len) {
+		if (*fmt != '%') {
+			if (i < len) buf[i++] = *fmt++;
+			continue;
+		}
+
+		fmt++; // Consume the '%'
+		if (*fmt == '\0') {
+			if (i < len) buf[i++] = '%';
+			break;
+		}
+
+		// Parse the format specifier
+		int width = 0;
+		char pad = ' ';
+
+		if (pf_isdigit(*fmt)) {
+			if (*fmt == '0') { pad = '0'; fmt++; }
+
+			while (pf_isdigit(*fmt)) {
+				width *= 10;
+				width += *fmt++ - '0';
+			}
+		}
+
+		char* s;
+		switch (*fmt) {
+		case 'c': // Char
+			if (i < len) buf[i++] = (char)va_arg(args, int);
+			break;
+		case 'd': // Int (TODO: %d for signed, %u for unsigned
+			s = pf_itoa(va_arg(args, unsigned int), 10);
+			goto string;
+		case 'x': // Unsigned hex int
+			s = pf_itoa(va_arg(args, unsigned int), 16);
+			goto string;
+		case 'f': // Float
+			s = pf_ftoa(va_arg(args, double));
+			goto string;
+		case 's': // String
+			s = va_arg(args, char*);
+		string: // Prints the string in s
+			if (s == NULL) s = "(null)";
+			while (*s != '\0' && i < len) buf[i++] = *s++;
+			break;
+		default: // Something else
+			if (i < len) buf[i++] = '%';
+			if (i < len) buf[i++] = *fmt;
+			break;
+		}
+
+		fmt++;
+	}
+
+	if (i < len) buf[i++] = '\0';
+
+	return i;
+}
+