new rng, some rework of I/O

10 files changed, 102 insertions, 22 deletions

diff --git a/boot/head.S b/boot/head.S
index 4d17f73..6149665 100644
--- a/boot/head.S
+++ b/boot/head.S
@@ -17,9 +17,9 @@ multiboot_header:
         .long 0
         .long 0
         .long 0
-        .long 320
-        .long 200
-        .long 32
+        .long 0 # screen height (don't care)
+        .long 0 # screen width (don't care)
+        .long 32 # screen BPP: MUST be 32
 
 .section .stack
 stack_bottom:                   # Stack grows up in addresses, so bottom is
diff --git a/drivers/include/vga.h b/drivers/include/vga.h
index b83ec95..8ea478b 100644
--- a/drivers/include/vga.h
+++ b/drivers/include/vga.h
@@ -33,6 +33,12 @@ enum vga_color_t {
 #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))
 
-void vga_init();
+struct vbe_info_t;
 
-void vga_drawpixel(int x, int y, uint32_t pix);
+void vga_init(struct vbe_info_t *vbe_mode_info);
+
+void vga_drawpixel(int x, int y, uint32_t color);
+
+void vga_clear(uint32_t color);
+
+extern const uint16_t *vga_width, *vga_height;
diff --git a/drivers/vga.c b/drivers/vga.c
index cfcd287..ccf0949 100644
--- a/drivers/vga.c
+++ b/drivers/vga.c
@@ -1,20 +1,42 @@
 #include <stddef.h>
 #include <stdlib.h>
+#include "log.h"
 #include "multiboot.h"
+#include "panic.h"
 #include "vga.h"
 
 static uint8_t *framebuffer = NULL;
 static uint16_t fb_width;
 static uint16_t fb_height;
+/* this is BYTES per pixel */
+static uint8_t  fb_bpp;
 
-void vga_drawpixel(int x, int y, uint32_t pixel)
+const uint16_t *vga_width = &fb_width;
+const uint16_t *vga_height = &fb_height;
+
+void vga_drawpixel(int x, int y, uint32_t col)
+{
+    ((uint32_t*)framebuffer)[y * fb_width + x] = col;
+}
+
+void vga_clear(uint32_t col)
 {
-    ((uint32_t*)framebuffer)[y * fb_width + x] = pixel;
+    uint8_t *p = framebuffer;
+    uint8_t *stop = framebuffer + fb_width * fb_height * fb_bpp;
+    while(p < stop)
+    {
+        *(uint32_t*)p = col;
+        p += fb_bpp;
+    }
 }
 
 void vga_init(struct vbe_info_t *vbe_mode_info)
 {
-    framebuffer = vbe_mode_info->physbase;
+    framebuffer = (uint8_t*)vbe_mode_info->physbase;
     fb_width = vbe_mode_info->Xres;
     fb_height = vbe_mode_info->Yres;
+    fb_bpp = vbe_mode_info->bpp / 8;
+    if(fb_bpp != 4)
+        panic("BPP *MUST* be 32!!!\n");
+    vga_clear(VGA_RGBPACK(0, 0, 0));
 }
diff --git a/kernel/include/log.h b/kernel/include/log.h
index fb29dd3..6953bee 100644
--- a/kernel/include/log.h
+++ b/kernel/include/log.h
@@ -1,3 +1,3 @@
-int log_putchar(char);
-int log_puts(const char*);
+void log_putchar(char);
+void log_puts(const char*);
 void log(const char*, ...);
diff --git a/kernel/include/timer.h b/kernel/include/timer.h
index a7459a6..bf2eddd 100644
--- a/kernel/include/timer.h
+++ b/kernel/include/timer.h
@@ -1,7 +1,12 @@
 #include <stdint.h>
 
-extern const uint64_t *current_tick;
+#define HZ 100
+#define PIT_FREQ 1193182
+
+extern volatile const uint64_t *current_tick;
 
 struct regs_t;
 
-void timer_init(void);
+void timer_init(uint32_t freq);
+
+void timer_delay(uint64_t ticks);
diff --git a/kernel/log.c b/kernel/log.c
index 3f509c5..efc945d 100644
--- a/kernel/log.c
+++ b/kernel/log.c
@@ -5,17 +5,15 @@
 
 #define BOCHS_PUTCHAR(ch) (outb(0xe9, ch))
 
-int log_putchar(int ch)
+void log_putchar(int ch)
 {
     BOCHS_PUTCHAR(ch);
-    return 0;
 }
 
-int log_puts(const char* str)
+void log_puts(const char* str)
 {
     while(*str)
         log_putchar(*str++);
-    return 0;
 }
 
 static char hex_table[16] = { '0', '1', '2', '3', '4', '5', '6', '7',
diff --git a/kernel/main.c b/kernel/main.c
index 9082859..d791da1 100644
--- a/kernel/main.c
+++ b/kernel/main.c
@@ -1,11 +1,13 @@
 #include <stdint.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include "gdt.h"
 #include "idt.h"
 #include "isr.h"
 #include "irq.h"
 #include "log.h"
 #include "multiboot.h"
+#include "panic.h"
 #include "pcspkr.h"
 #include "ps2.h"
 #include "timer.h"
@@ -36,15 +38,18 @@ void main(struct multiboot_info_t *hdr, uint32_t magic)
     irq_init();
 
     /* initialize other drivers */
-    timer_init();
+    timer_init(HZ);
     ps2_init();
 
     asm("sti");
 
     printf("Boot finished.\n");
 
-    for(int i=0;i<50;++i)
-        vga_drawpixel(i, i, VGA_RGBPACK(255, 0, 0));
+    printf("Testing RNG...\n");
+    srand(*current_tick);
+
+    for(int i=0;i>=0;++i)
+        vga_drawpixel(rand() % *vga_width, rand() % *vga_height, rand() % 0xFFFFFF);
 
     printf("Testing keyboard LED's...\n");
 
diff --git a/kernel/timer.c b/kernel/timer.c
index 571fcbe..2fbd8eb 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1,10 +1,11 @@
 #include <stdint.h>
+#include "io.h"
 #include "isr.h"
 #include "timer.h"
 
-uint64_t current_tick_data = 0;
+volatile uint64_t current_tick_data = 0;
 
-const uint64_t *current_tick = &current_tick_data;
+volatile const uint64_t *current_tick = &current_tick_data;
 
 static void timer_callback(struct regs_t regs)
 {
@@ -12,7 +13,24 @@ static void timer_callback(struct regs_t regs)
     ++current_tick_data;
 }
 
-void timer_init(void)
+void timer_init(uint32_t freq)
 {
     set_interrupt_handler(IRQ(0), timer_callback);
+
+    current_tick_data = 0;
+
+    uint32_t divisor = PIT_FREQ / freq;
+
+    uint8_t hi = (divisor >> 8) & 0xFF;
+    uint8_t lo = (divisor >> 0) & 0xFF;
+
+    outb(0x43, 0x36);
+    outb(0x40, lo);
+    outb(0x40, hi);
+}
+
+void timer_delay(uint64_t ticks)
+{
+    uint64_t end = *current_tick + ticks;
+    while(*current_tick <= end);
 }
diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index 146b4b8..0a3d559 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -2,3 +2,6 @@
 
 /* NOT reentrant! */
 char* itoa(int val, int base);
+
+int rand(void);
+void srand(unsigned int);
diff --git a/libc/stdlib.c b/libc/stdlib.c
index 356fc33..49f61f1 100644
--- a/libc/stdlib.c
+++ b/libc/stdlib.c
@@ -13,3 +13,26 @@ char* itoa(int val, int base)
 
     return &buf[i+1];
 }
+
+static int rand_state = 42;
+
+/* some constants for the RNG */
+#define A 48271
+#define M 2147483647
+#define Q (M/A)
+#define R (M%A)
+
+int rand(void)
+{
+    int tmp = A * (rand_state % Q) - R * (rand_state / Q);
+    if(tmp >= 0)
+        rand_state = tmp;
+    else
+        rand_state = tmp + M;
+    return rand_state;
+}
+
+void srand(unsigned int seed)
+{
+    rand_state = seed;
+}