fix RNG with zero seed, rename VGA->GFX

7 files changed, 33 insertions, 28 deletions

diff --git a/OBJ b/OBJ
index 06a3d33..fbceaf2 100644
--- a/OBJ
+++ b/OBJ
@@ -1,8 +1,8 @@
 boot/head.o
+drivers/gfx.o
 drivers/pcspkr.o
 drivers/ps2.o
 drivers/tty.o
-drivers/vga.o
 kernel/gdt-as.o
 kernel/gdt.o
 kernel/idt-as.o
diff --git a/boot/head.S b/boot/head.S
index 6149665..8bd42f1 100644
--- a/boot/head.S
+++ b/boot/head.S
@@ -16,7 +16,7 @@ multiboot_header:
         .long 0
         .long 0
         .long 0
-        .long 0
+        .long 0 # 1=text mode
         .long 0 # screen height (don't care)
         .long 0 # screen width (don't care)
         .long 32 # screen BPP: MUST be 32
diff --git a/drivers/vga.c b/drivers/gfx.c
index ccf0949..538dadb 100644
--- a/drivers/vga.c
+++ b/drivers/gfx.c
@@ -3,7 +3,7 @@
 #include "log.h"
 #include "multiboot.h"
 #include "panic.h"
-#include "vga.h"
+#include "gfx.h"
 
 static uint8_t *framebuffer = NULL;
 static uint16_t fb_width;
@@ -11,15 +11,15 @@ static uint16_t fb_height;
 /* this is BYTES per pixel */
 static uint8_t  fb_bpp;
 
-const uint16_t *vga_width = &fb_width;
-const uint16_t *vga_height = &fb_height;
+const uint16_t *gfx_width = &fb_width;
+const uint16_t *gfx_height = &fb_height;
 
-void vga_drawpixel(int x, int y, uint32_t col)
+void gfx_drawpixel(int x, int y, uint32_t col)
 {
     ((uint32_t*)framebuffer)[y * fb_width + x] = col;
 }
 
-void vga_clear(uint32_t col)
+void gfx_clear(uint32_t col)
 {
     uint8_t *p = framebuffer;
     uint8_t *stop = framebuffer + fb_width * fb_height * fb_bpp;
@@ -30,7 +30,7 @@ void vga_clear(uint32_t col)
     }
 }
 
-void vga_init(struct vbe_info_t *vbe_mode_info)
+void gfx_init(struct vbe_info_t *vbe_mode_info)
 {
     framebuffer = (uint8_t*)vbe_mode_info->physbase;
     fb_width = vbe_mode_info->Xres;
@@ -38,5 +38,5 @@ void vga_init(struct vbe_info_t *vbe_mode_info)
     fb_bpp = vbe_mode_info->bpp / 8;
     if(fb_bpp != 4)
         panic("BPP *MUST* be 32!!!\n");
-    vga_clear(VGA_RGBPACK(0, 0, 0));
+    gfx_clear(VGA_RGBPACK(0, 0, 0));
 }
diff --git a/drivers/include/vga.h b/drivers/include/gfx.h
index 8ea478b..bafd7a3 100644
--- a/drivers/include/vga.h
+++ b/drivers/include/gfx.h
@@ -22,23 +22,19 @@ enum vga_color_t {
 #define VGA_WIDTH  80
 #define VGA_HEIGHT 25
 
-#define VGA_SEQ_INDEX           0x3C4
-#define VGA_SEQ_DATA            0x3C5
-#define VGA_GC_INDEX            0x3CE
-#define VGA_GC_DATA             0x3CF
-#define VGA_CRTC_INDEX          0x3D4
-#define VGA_CRTC_DATA           0x3D5
-
 #define VGA_MAKE_COLOR(fg, bg) (fg | bg << 4)
 #define VGA_MAKE_ENTRY(ch, col) (((uint16_t)ch)|((uint16_t)col<<8))
 #define VGA_RGBPACK(r, g, b)  ((r << 16)|(g << 8)|(b << 0))
 
+#define GFX_WHITE 0xFFFFFF
+#define GFX_BLACK 0x000000
+
 struct vbe_info_t;
 
-void vga_init(struct vbe_info_t *vbe_mode_info);
+void gfx_init(struct vbe_info_t *vbe_mode_info);
 
-void vga_drawpixel(int x, int y, uint32_t color);
+void gfx_drawpixel(int x, int y, uint32_t color);
 
-void vga_clear(uint32_t color);
+void gfx_clear(uint32_t color);
 
-extern const uint16_t *vga_width, *vga_height;
+extern const uint16_t *gfx_width, *gfx_height;
diff --git a/drivers/tty.c b/drivers/tty.c
index 7bce7e7..ae15778 100644
--- a/drivers/tty.c
+++ b/drivers/tty.c
@@ -1,9 +1,9 @@
 #include <stdint.h>
 #include <stdio.h>
+#include "gfx.h"
 #include "io.h"
 #include "panic.h"
 #include "tty.h"
-#include "vga.h"
 
 static int term_x, term_y;
 static uint8_t term_col;
diff --git a/kernel/main.c b/kernel/main.c
index d791da1..6cad670 100644
--- a/kernel/main.c
+++ b/kernel/main.c
@@ -2,6 +2,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include "gdt.h"
+#include "gfx.h"
 #include "idt.h"
 #include "isr.h"
 #include "irq.h"
@@ -12,23 +13,24 @@
 #include "ps2.h"
 #include "timer.h"
 #include "tty.h"
-#include "vga.h"
 
 void main(struct multiboot_info_t *hdr, uint32_t magic)
 {
     /* this should go to port e9, which is the Bochs debug port */
     printf("Testing early I/O\n");
 
-    /* initialize the TTY first, no real harm can be done */
-    tty_init();
+    printf("GFX init\n");
+    int gfx_status = gfx_init((struct vbe_info_t*)hdr->vbe_mode_info);
+
+    /* if graphical initialization fails, fall back to text mode */
+    if(!gfx_status)
+        tty_init();
 
     if(magic != 0x2BADB002)
     {
         panic("Multiboot magic invalid");
     }
 
-    vga_init((struct vbe_info_t*)hdr->vbe_mode_info);
-
     /* then the descriptor tables so we can do more useful stuff */
     gdt_init();
     idt_init();
@@ -49,7 +51,13 @@ void main(struct multiboot_info_t *hdr, uint32_t magic)
     srand(*current_tick);
 
     for(int i=0;i>=0;++i)
-        vga_drawpixel(rand() % *vga_width, rand() % *vga_height, rand() % 0xFFFFFF);
+    {
+        int rx = rand() % *gfx_width;
+        int ry = rand() % *gfx_height;
+
+        gfx_drawpixel(rx, ry, rand() % 0xFFFFFF);
+    }
+    gfx_clear(0xffffff);
 
     printf("Testing keyboard LED's...\n");
 
diff --git a/libc/stdlib.c b/libc/stdlib.c
index 49f61f1..ca890b4 100644
--- a/libc/stdlib.c
+++ b/libc/stdlib.c
@@ -34,5 +34,6 @@ int rand(void)
 
 void srand(unsigned int seed)
 {
-    rand_state = seed;
+    /* prevent a zero seed */
+    rand_state = (!seed?42:seed);
 }