libk: create a subset libc for kernel use

Create a subset of the C library for use inside the kernel.

Signed-off-by: Danny Holman <dholman@gymli.org>

1 files changed, 78 insertions, 0 deletions

diff --git a/libk/io.c b/libk/io.c
new file mode 100644
index 0000000..eedc171
--- /dev/null
+++ b/libk/io.c
@@ -0,0 +1,78 @@
+#include <libk/io.h>
+#include <libk/string.h>
+#include <kernel/video/framebuffer.h>
+#include <kernel/tty/tty_vga.h>
+
+char* convert(unsigned int num, int base) {
+        static char rep[] = "0123456789ABCDEF";
+        static char buffer[50];
+        char *ptr;
+
+        ptr = &buffer[49];
+        *ptr = '\0';
+
+        do {
+                *--ptr = rep[num%base];
+                num /= base;
+        } while (num != 0);
+
+        return ptr;
+}
+
+int vkprintf(const char *fmt, va_list args) {
+        char *s;
+        int i;
+
+        char buffer[4096];
+        memset(buffer, 0, 4096);
+        for (size_t n = 0; n < strlen(fmt); n++) {
+                if (fmt[n] != '%') {
+                        buffer[strlen(buffer)] = fmt[n];
+                        continue;
+                } else {
+                        n++;
+                }
+
+                switch (fmt[n]) {
+                        case 'c':
+                                i = va_arg(args, int);
+                                buffer[strlen(buffer)] = i;
+                                break;
+                        case 's':
+                                s = va_arg(args, char*);
+                                strcat(buffer, s);
+                                break;
+                        case 'd':
+                                i = va_arg(args, int);
+                                if (i < 0) {
+                                        i = -i;
+                                        strcat(buffer, "-");
+                                }
+                                strcat(buffer, convert(i, 10));
+                                break;
+                        case 'o':
+                                i = va_arg(args, unsigned int);
+                                strcat(buffer, convert(i, 10));
+                                break;
+                        case 'x':
+                                i = va_arg(args, unsigned int);
+                                strcat(buffer, convert(i, 16));
+                                break;
+                }
+        }
+        //tty_write(buffer, strlen(buffer));
+        fb_write(buffer, strlen(buffer));
+        memset(buffer, 0, 4096);
+        return 0;
+}
+
+int kprintf(const char *fmt, ...) {
+        va_list args;
+        int done;
+
+        va_start(args, fmt);
+        done = vkprintf(fmt, args);
+        va_end(args);
+
+        return done;
+}