kprint

kern/kprint.c

@@ -0,0 +1,103 @@
+#include <stdarg.h>
+#include <stdbool.h>
+
+static void append_char(char **buf, size_t *remaining, char c) {
+    if (*remaining > 1) { // Leave space for null terminator
+        **buf = c;
+        (*buf)++;
+        (*remaining)--;
+    }
+}
+
+static void append_str(char **buf, size_t *remaining, const char *str) {
+    while (*str) {
+        append_char(buf, remaining, *str++);
+    }
+}
+
+static void append_int(char **buf, size_t *remaining, int value, int base) {
+    char        tmp[32];
+    const char *digits = "0123456789abcdef";
+    bool        neg = false;
+    int         i = 0;
+
+    if (base == 10 && value < 0) {
+        neg = true;
+        value = -value;
+    }
+
+    do {
+        tmp[i++] = digits[value % base];
+        value /= base;
+    } while (value && i < (int)sizeof(tmp));
+
+    if (neg) {
+        tmp[i++] = '-';
+    }
+
+    while (i--) {
+        append_char(buf, remaining, tmp[i]);
+    }
+}
+
+int kvsnprintf(char *buf, size_t size, const char *fmt, va_list args) {
+    char  *p = buf;
+    size_t remaining = size;
+
+    while (*fmt) {
+        if (*fmt != '%') {
+            append_char(&p, &remaining, *fmt++);
+            continue;
+        }
+        fmt++; // skip '%'
+
+        switch (*fmt) {
+        case 's':
+            append_str(&p, &remaining, va_arg(args, const char *));
+            break;
+        case 'd':
+            append_int(&p, &remaining, va_arg(args, int), 10);
+            break;
+        case 'x':
+            append_int(&p, &remaining, va_arg(args, unsigned int), 16);
+            break;
+        case 'c':
+            append_char(&p, &remaining, (char)va_arg(args, int));
+            break;
+        case '%':
+            append_char(&p, &remaining, '%');
+            break;
+        default:
+            append_char(&p, &remaining, '?');
+            break;
+        }
+        fmt++;
+    }
+
+    if (remaining > 0) {
+        *p = '\0';
+    } else {
+        buf[size - 1] = '\0';
+    }
+
+    return (int)(p - buf);
+}
+
+int ksnprintf(char *buf, size_t size, const char *fmt, ...) {
+    va_list args;
+    va_start(args, fmt);
+    int ret = kvsnprintf(buf, size, fmt, args);
+    va_end(args);
+    return ret;
+}
+
+void kprintf(const char *fmt, ...) {
+    char    buffer[256];
+    va_list args;
+    va_start(args, fmt);
+    kvsnprintf(buffer, sizeof(buffer), fmt, args);
+    va_end(args);
+
+    // Now send buffer to your console/serial output
+    console_write(buffer);
+}