Create vesa.c

Add the implementation for a basic VLB VESA VBE driver for these video cards

kernel/vesa.c

@@ -0,0 +1,98 @@
+#include "vesa.h"
+#include "io.h"
+#include "print.h"
+
+// VESA mode and controller information
+#define VESA_BIOS_INT 0x10
+#define VESA_BIOS_FUNC 0x4F
+
+// Function to call BIOS with specific VESA function
+static bool vesa_bios_call(uint16_t function, uint16_t* eax, uint32_t* ebx, uint32_t* ecx, uint32_t* edx) {
+    // Set up registers for VESA function call
+    __asm__ __volatile__(
+        "movw %1, %%ax\n"           // Move function number into AX
+        "int $0x10\n"                // Call BIOS interrupt 0x10 (VESA)
+        "movw %%ax, %0\n"            // Move return value in AX to the return variable
+        : "=m"(*eax)                 // Output operand (eax)
+        : "m"(function)              // Input operand (function number)
+        : "%eax", "%ebx", "%ecx", "%edx", "memory"
+    );
+    // Check for success (return values vary depending on the function)
+    return *eax == 0x004F;
+}
+
+// Set the VESA video mode
+bool vesa_set_mode(uint16_t mode) {
+    uint16_t eax = VBE_FUNCTION_SET_MODE;
+    uint32_t ebx = mode;
+    uint32_t ecx = 0;
+    uint32_t edx = 0;
+    
+    if (vesa_bios_call(VBE_FUNCTION_SET_MODE, &eax, &ebx, &ecx, &edx)) {
+        return true;
+    }
+    return false;
+}
+
+// Get the VESA mode information
+bool vesa_get_mode_info(uint16_t mode, vbe_mode_info_t* info) {
+    uint16_t eax = VBE_FUNCTION_GET_MODE_INFO;
+    uint32_t ebx = mode;
+    uint32_t ecx = 0;
+    uint32_t edx = 0;
+
+    if (vesa_bios_call(VBE_FUNCTION_GET_MODE_INFO, &eax, &ebx, &ecx, &edx)) {
+        // Copy the information into the provided struct
+        uint32_t base = (uint32_t)info;
+        __asm__ __volatile__(
+            "movw %%bx, %%es:%%di\n"
+            : 
+            : "b" (base)
+            : "%es", "%di", "memory"
+        );
+        return true;
+    }
+    return false;
+}
+
+// Get the VESA controller information
+bool vesa_get_controller_info(vbe_controller_info_t* info) {
+    uint16_t eax = VBE_FUNCTION_GET_CONTROLLER_INFO;
+    uint32_t ebx = 0;
+    uint32_t ecx = 0;
+    uint32_t edx = 0;
+
+    if (vesa_bios_call(VBE_FUNCTION_GET_CONTROLLER_INFO, &eax, &ebx, &ecx, &edx)) {
+        // Copy controller information into the provided struct
+        uint32_t base = (uint32_t)info;
+        __asm__ __volatile__(
+            "movw %%bx, %%es:%%di\n"
+            : 
+            : "b" (base)
+            : "%es", "%di", "memory"
+        );
+        return true;
+    }
+    return false;
+}
+
+// Return pointer to the VESA framebuffer
+void* vesa_get_framebuffer(void) {
+    vbe_mode_info_t mode_info;
+    if (vesa_get_mode_info(0x101, &mode_info)) {
+        return (void*)mode_info.PhysBasePtr;
+    }
+    return NULL;
+}
+
+// Clear the screen with a color
+void vesa_clear_screen(uint32_t color) {
+    uint32_t* framebuffer = (uint32_t*)vesa_get_framebuffer();
+    if (framebuffer) {
+        for (int y = 0; y < 480; y++) { // For 640x480 mode
+            for (int x = 0; x < 640; x++) {
+                framebuffer[y * 640 + x] = color;
+            }
+        }
+    }
+}