Scroll some pixels on the fuckin screenHEADmain

5 files changed, 113 insertions, 28 deletions

diff --git a/src/boot.asm b/src/boot.asm
index e723d61..3d25240 100644
--- a/src/boot.asm
+++ b/src/boot.asm
@@ -1,4 +1,4 @@
-;> The Multiboot header must be contained completely within the first 8192 bytes of the OS 
+;> The Multiboot header must be contained completely within the first 8192 bytes of the OS
 ;> image, and must be longword (32-bit) aligned.
 MULTIBOOT_ALIGN_TO_PAGE:   equ 1 << 0
 MULTIBOOT_MEMORY_DESCRIBE: equ 1 << 1
@@ -9,7 +9,7 @@ MULTIBOOT_CHECKSUM:        equ -(MULTIBOOT_MAGIC + MULTIBOOT_FLAGS)
 MULTIBOOT_VIDEO_TYPE:      equ 0
 MULTIBOOT_GODS_WIDTH:      equ 640
 MULTIBOOT_GODS_HEIGHT:     equ 480
-MULTIBOOT_VIDEO_BPP:       equ 16
+MULTIBOOT_VIDEO_BPP:       equ 24
 
 ; We don't set flags[16] because we assemble to ELF32 so header_addr, etc is useless to us
 ; (at least at the moment).
@@ -39,6 +39,8 @@ section .text
 global _start:function (_start.end - _start)
 _start:
     mov esp, stack_top
+    push ebx
+    push eax
     extern cmain
     call cmain
     cli
diff --git a/src/io.c b/src/io.c
index 1d9db60..d1206c3 100644
--- a/src/io.c
+++ b/src/io.c
@@ -1,6 +1,10 @@
 #include <stdint.h>
 #include "utils.h"
 
+#define PORT 0x3f8                   // COM1
+#define LINE_STATUS_REGISTER         PORT + 5
+#define TRANSMITTER_EMPTY_BITMASK    0b00100000
+
 uint8_t inportb(uint16_t port) {
     uint8_t r;
     asm("inb %1, %0" : "=a" (r) : "dN" (port));
@@ -9,4 +13,44 @@ uint8_t inportb(uint16_t port) {
 
 void outportb(uint16_t port, uint8_t data) {
     asm("outb %1, %0" : : "dN" (port), "a" (data));
-}
\ No newline at end of file
+}
+
+void init_serial() {
+    outportb(PORT + 1, 0x00); // Disable all interrupts
+    outportb(PORT + 3, 0x80); // Enable DLAB (set baud rate divisor)
+
+    // Set divisor to 3 -> (115200 / 3) = 38400
+    outportb(PORT + 0, 0x03); // LSB
+    outportb(PORT + 1, 0x00); // MSB
+
+    outportb(PORT + 3, 0x03); // Character length is 8 bits, no parity, one stop bit
+    outportb(PORT + 2, 0xC7); // Enable FIFO, clear them, with 14-byte threshold
+
+//  TODO: GDT and IDT in order to setup COM1 interrupts.
+//        For now, though, we POLLLLL that mf.
+//     outportb(PORT + 4, 0x0B); // IRQs enabled, RTS/DSR set
+
+    outportb(PORT + 4, 0x1E); // Set in loopback mode, test the serial chip
+    outportb(PORT + 0, 0xAE); // Test serial chip (send byte 0xAE and check if serial returns same byte)
+    macaroni_assert(inportb(PORT + 0) == 0xAE, "0xAE expected from serial initizliation");
+    outportb(PORT + 4, 0x0F);
+}
+
+int serial_tx_empty(void) {
+    return inportb(LINE_STATUS_REGISTER) & TRANSMITTER_EMPTY_BITMASK;
+}
+
+void serial_putc(char c) {
+    while (!serial_tx_empty());
+    outportb(PORT, c);
+}
+
+void serial_puts(const char* s) {
+    while (*s) serial_putc(*s++);
+}
+
+void serial_puthex(uint32_t h) {
+    serial_puts("0x");
+    for (int i = 28; i >= 0; i -= 4)
+        serial_putc("0123456789abcdef"[(h >> i) & 0xF]);
+}
diff --git a/src/kernel.c b/src/kernel.c
index 2c2afcc..dacc47e 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -1,28 +1,33 @@
-#include "utils.h"
-#include "multiboot.h"
 #include <stddef.h>
 #include <stdint.h>
 #include <stdbool.h>
+#include "utils.h"
+#include "multiboot.h"
+#include "io.h"
+#include "video.h"
 
-void validate_multiboot
+void validate_multiboot(multiboot_info_t* p_multiboot_info, uint32_t magic_response) {
+    macaroni_assert(magic_response == 0x2BADB002, "im not a bad boo twooo");
+    macaroni_assert(p_multiboot_info->flags != 0, "version flag being zero is not a good sign");
+}
 
-void cmain(void) {
-    uint32_t magic_response;
-    multiboot_info_t* p_multiboot_info;
-    asm("\t movl %%eax,%0" : "=r"(magic_response));
-    asm("\t movl %%ebx,%0" : "=r"(p_multiboot_info));
+// Stack: [...Bottom] (%ebx, %eax) [...Top]
+void cmain(uint32_t magic_response, multiboot_info_t* p_multiboot_info) {
+    validate_multiboot(p_multiboot_info, magic_response);
 
-    macaroni_assert(magic_response == 0x2BADB002, "im not a bad boo twooo");
-    macaroni_assert(p_multiboot_info->framebuffer_width == 640, "not gods width");
-    macaroni_assert(p_multiboot_info->framebuffer_height == 480, "not gods height");
-    macaroni_assert(p_multiboot_info->framebuffer_bpp == 16, "not gods bpp");
-    macaroni_assert(p_multiboot_info->framebuffer_type == MULTIBOOT_FRAMEBUFFER_TYPE_RGB, "not gods fbtype");
-    macaroni_assert(p_multiboot_info->framebuffer_red_field_position == 1, "bpp not formatted correctly");
+    init_serial();
+    init_video(p_multiboot_info);
 
-    void *fb = (void *) (unsigned long) p_multiboot_info->framebuffer_addr;
-    uint8_t* pixel = fb;
-    for (int i = 0; i < 10000; i++) {
-        *(pixel + i) = i * 2;
+    macaroni_color colors[] = { RED, GREEN, BLUE };
+    uint32_t i = 0;
+    while(true) {
+        for (uint32_t y = 0; y < MULTIBOOT_GODS_HEIGHT; y++) {
+            for (uint32_t x = 0; x < MULTIBOOT_GODS_WIDTH; x++) {
+                put_pixel(colors[(i + y / 10) % 3], x, y);
+            }
+        }
+        // "sleep"
+        for (int _k = 0; _k < 10000000; _k++) {}
+        i++;
     }
-
 }
diff --git a/src/utils.c b/src/utils.c
index 63b0b56..bf1ff13 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -1,14 +1,15 @@
 #include "utils.h"
+#include "io.h"
 
-void macaroni_panic(char* msg) {
+void macaroni_panic(const char* msg) {
     // we'll do something with msg later.
     // while(true){ asm("nop\n\t"); }
+    serial_puts(msg);
     asm("int $0x13");
 }
 
-void macaroni_assert(bool condition, char* msg) {
-    if (condition) {
-        return;
+void macaroni_assert(bool condition, const char* msg) {
+    if (!condition) {
+        macaroni_panic(msg);
     }
-    macaroni_panic("thisisatest");
-}
\ No newline at end of file
+}
diff --git a/src/video.c b/src/video.c
new file mode 100644
index 0000000..be01f6d
--- /dev/null
+++ b/src/video.c
@@ -0,0 +1,33 @@
+#include "video.h"
+#include "utils.h"
+#include "io.h"
+
+void init_video(multiboot_info_t* p_multiboot_info) {
+    #ifdef DEBUG
+    macaroni_assert(p_multiboot_info->framebuffer_width == MULTIBOOT_GODS_WIDTH, "not gods width");
+    macaroni_assert(p_multiboot_info->framebuffer_height == MULTIBOOT_GODS_HEIGHT, "not gods height");
+    macaroni_assert(p_multiboot_info->framebuffer_bpp == MULTIBOOT_VIDEO_BPP, "not gods bpp");
+    macaroni_assert(p_multiboot_info->framebuffer_type == MULTIBOOT_FRAMEBUFFER_TYPE_RGB, "not video fbtype");
+    #endif
+
+    #ifdef DEBUG
+    serial_puthex((uint32_t) p_multiboot_info->framebuffer_red_field_position);
+    serial_puthex((uint32_t) p_multiboot_info->framebuffer_red_mask_size);
+    serial_puthex((uint32_t) p_multiboot_info->framebuffer_green_field_position);
+    serial_puthex((uint32_t) p_multiboot_info->framebuffer_green_mask_size);
+    serial_puthex((uint32_t) p_multiboot_info->framebuffer_blue_field_position);
+    serial_puthex((uint32_t) p_multiboot_info->framebuffer_blue_mask_size);
+    serial_puthex((uint32_t) p_multiboot_info->framebuffer_bpp);
+    serial_puthex((uint32_t) p_multiboot_info->framebuffer_pitch);
+    #endif // DEBUG
+
+    video_framebuffer = (uint8_t*) (uint32_t) p_multiboot_info->framebuffer_addr;
+    pixel_width = (p_multiboot_info->framebuffer_bpp / 8);
+    pitch = p_multiboot_info->framebuffer_pitch;
+}
+
+void put_pixel(macaroni_color color, uint16_t x, uint16_t y) {
+    video_framebuffer[x * pixel_width + y * pitch] = color & 0xFF;
+    video_framebuffer[x * pixel_width + y * pitch + 1] = (color >> 8) & 0xFF;
+    video_framebuffer[x * pixel_width + y * pitch + 2] = (color >> 16) & 0xFF;
+}