add klog module to print kernel messages

src/fb.c

@@ -33,6 +33,11 @@ void fb_init(uint32_t * addr, uint32_t width, uint32_t height, uint32_t pitch)
     fb_clear();
 }
 
+uint32_t * fb_addr(void)
+{
+    return fb.addr;
+}
+
 bool fb_ready(void)
 {
     return fb.addr != NULL;

src/fb.h

@@ -6,6 +6,7 @@
 
 void fb_init(uint32_t * addr, uint32_t width, uint32_t height, uint32_t pitch);
 bool fb_ready(void);
+uint32_t * fb_addr(void);
 uint32_t fb_width(void);
 uint32_t fb_height(void);
 void fb_blend_alpha8(const uint8_t * bitmap, int width, int height, int pitch, int x, int y, uint8_t r, uint8_t g, uint8_t b);

src/hos_main.c

@@ -1,8 +1,7 @@
 #include <stdint.h>
 #include "fb.h"
-#include "fb_text.h"
 #include "mbinfo.h"
-#include "kfont.h"
+#include "klog.h"
 
 void hos_main(uint32_t mbinfo_addr)
 {
@@ -11,5 +10,6 @@ void hos_main(uint32_t mbinfo_addr)
     {
         return;
     }
-    fb_text_render_char('H', 10, 10, 0xFFu, 0x88u, 0u);
+    klog_init();
+    klog_printf("Welcome to HOS!\n");
 }

src/klog.c

@@ -0,0 +1,103 @@
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <stdarg.h>
+#include "klog.h"
+#include "kfont.h"
+#include "fb.h"
+#include "fb_text.h"
+#include "stream.h"
+#include "hos_printf.h"
+#include "mem.h"
+
+static struct {
+    size_t console_width;
+    size_t console_height;
+    size_t x;
+    size_t y;
+    bool need_shift;
+} klog;
+
+static void shift_line(void)
+{
+    uint32_t * fb = fb_addr();
+    uint32_t w = fb_width();
+    size_t console_fb_line_words = w * kfont.line_height;
+    for (size_t row = 0u; row < klog.console_height; row++)
+    {
+        memcpy32(fb, fb + console_fb_line_words, console_fb_line_words);
+        fb += console_fb_line_words;
+    }
+    fb_fill(0, kfont.line_height * (klog.console_height - 1u), w, kfont.line_height, 0u, 0x2Cu, 0x55u);
+}
+
+static void klog_fb_write1(char c)
+{
+    if (klog.need_shift)
+    {
+        shift_line();
+        klog.need_shift = false;
+    }
+    if (c == '\n')
+    {
+        if (klog.y == (klog.console_height - 1u))
+        {
+            klog.need_shift = true;
+        }
+        else
+        {
+            klog.y++;
+        }
+        klog.x = 0u;
+    }
+    else
+    {
+        int px = klog.x * kfont.advance;
+        int py = klog.y * kfont.line_height;
+        fb_text_render_char(c, px, py, 0xFFu, 0x80u, 0u);
+        klog.x++;
+        if (klog.x == klog.console_width)
+        {
+            if (klog.y == (klog.console_height - 1u))
+            {
+                klog.need_shift = true;
+            }
+            else
+            {
+                klog.y++;
+            }
+            klog.x = 0u;
+        }
+    }
+}
+
+static void klog_fb_write(const char * src, size_t length)
+{
+    for (size_t i = 0u; i < length; i++)
+    {
+        klog_fb_write1(src[i]);
+    }
+}
+
+static const stream_t klog_fb_stream = {
+    klog_fb_write,
+    klog_fb_write1,
+};
+
+void klog_init(void)
+{
+    klog.console_width = fb_width() / kfont.advance;
+    klog.console_height = fb_height() / kfont.line_height;
+    klog.x = 0u;
+    klog.y = 0u;
+    klog.need_shift = false;
+    fb_fill(0, 0, fb_width(), fb_height(), 0u, 0x2Cu, 0x55u);
+}
+
+void klog_printf(const char * fmt, ...)
+{
+    va_list va;
+    va_start(va, fmt);
+    hos_vprintf(&klog_fb_stream, fmt, va);
+    va_end(va);
+}

src/klog.h

@@ -0,0 +1,7 @@
+#ifndef KLOG_H
+#define KLOG_H
+
+void klog_init(void);
+void klog_printf(const char * fmt, ...);
+
+#endif

src/mem.h

@@ -12,6 +12,17 @@ static inline void memcpy(void * dest, const void * src, size_t n)
             : "memory");
 }
 
+static inline void memcpy32(void * dest, const void * src, size_t count)
+{
+    uint32_t r0, r1, r2;
+    __asm__ __volatile__ (
+            "cld\n\t"
+            "rep movsd"
+            : "=&c" (r0), "=&S" (r1), "=&D" (r2)
+            : "2" (dest), "1" (src), "0" (count)
+            : "memory");
+}
+
 static inline void * memmove(void * dest, const void * src, size_t count)
 {
     return __builtin_memmove(dest, src, count);