[fpu][bochs][sys] FPU enabled, line drawing function, abs(), max()

kernel/core/fpu.c

@@ -0,0 +1,20 @@
+/*
+ * vim:tabstop=4
+ * vim:noexpandtab
+ */
+#include <system.h>
+
+void
+set_fpu_cw(const uint16_t cw) {
+	__asm__ __volatile__("fldcw %0" :: "m"(cw));
+}
+
+void
+enable_fpu() {
+	size_t cr4;
+	/* Trust me, we have an FPU */
+	__asm__ __volatile__ ("mov %%cr4, %0" : "=r"(cr4));
+	cr4 |= 0x200;
+	__asm__ __volatile__ ("mov %0, %%cr4" :: "r"(cr4));
+	set_fpu_cw(0x37F);
+}

kernel/core/shell.c

@@ -222,6 +222,20 @@ start_shell() {
 				} else {
 					bochs_draw_logo(argv[1]);
 				}
+			} else if (!strcmp(cmd, "line")) {
+				if (tokenid < 5) {
+					bochs_draw_line(0,1024,0,768, 0xFFFFFF);
+				} else {
+					bochs_draw_line(atoi(argv[1]),atoi(argv[2]),atoi(argv[3]),atoi(argv[4]),0xFFFFFF);
+				}
+			} else if (!strcmp(cmd, "boredom")) {
+				for (int derp = 0; derp < 30; ++derp) {
+					int x0 = krand() % 1024;
+					int x1 = krand() % 1024;
+					int y0 = krand() % 768;
+					int y1 = krand() % 768;
+					bochs_draw_line(x0,x1,y0,y1, krand() % 0xFFFFFF);
+				}
 			} else {
 				kprintf("Unrecognized command: %s\n", cmd);
 			}

kernel/core/system.c

@@ -24,6 +24,23 @@ memcpy(
 	return dest;
 }
 
+int
+max(int a, int b) {
+	return (a > b) ? a : b;
+}
+
+int
+abs(int a) {
+	return (a >= 0) ? a : -a;
+}
+
+void
+swap(int *a, int *b) {
+	int t = *a;
+	*a = *b;
+	*b = t;
+}
+
 void *
 memmove(
 		void * restrict dest,

kernel/core/video/bochs.c

@@ -188,6 +188,7 @@ bochs_write_char(
 	__asm__ __volatile__ ("sti");
 }
 
+/* This is mapped to ANSI */
 uint32_t bochs_colors[16] = {
 	/* black  */ 0x000000,
 	/* red    */ 0xcc0000,
@@ -318,3 +319,25 @@ void bochs_write(char c) {
 	draw_cursor();
 	__asm__ __volatile__ ("sti");
 }
+
+
+void bochs_draw_line(uint16_t x0, uint16_t x1, uint16_t y0, uint16_t y1, uint32_t color) {
+	int deltax = abs(x1 - x0);
+	int deltay = abs(y1 - y0);
+	int sx = (x0 < x1) ? 1 : -1;
+	int sy = (y0 < y1) ? 1 : -1;
+	int error = deltax - deltay;
+	while (1) {
+		bochs_set_point(x0, y0, color);
+		if (x0 == x1 && y0 == y1) break;
+		int e2 = 2 * error;
+		if (e2 > -deltay) {
+			error -= deltay;
+			x0 += sx;
+		}
+		if (e2 < deltax) {
+			error += deltax;
+			y0 += sy;
+		}
+	}
+}

kernel/include/system.h

@@ -16,6 +16,9 @@ extern void *sbrk(uintptr_t increment);
 extern uint16_t pci_get_lfb_addr(uint16_t id);
 
 /* Kernel Main */
+extern int max(int,int);
+extern int abs(int);
+extern void swap(int *, int *);
 extern void *memcpy(void *restrict dest, const void *restrict src, size_t count);
 extern void *memmove(void *restrict dest, const void *restrict src, size_t count);
 extern void *memset(void *dest, int val, size_t count);
@@ -213,7 +216,13 @@ extern void bochs_term_clear();
 extern void bochs_write(char c);
 extern void bochs_reset_colors();
 extern void bochs_set_colors(uint8_t, uint8_t);
+extern void bochs_draw_line(uint16_t,uint16_t,uint16_t,uint16_t,uint32_t);
 
 extern uint8_t number_font[][12];
 
+/* Floating Point Unit */
+
+void set_fpu_cw(const uint16_t);
+void enable_fpu();
+
 #endif

kernel/main.c

@@ -108,6 +108,7 @@ int main(struct multiboot *mboot_ptr, uint32_t mboot_mag, uintptr_t esp)
 	paging_install(mboot_ptr->mem_upper);	/* Paging */
 	heap_install();							/* Kernel heap */
 	tasking_install();						/* Multi-tasking */
+	enable_fpu();
 
 	/* Kernel Version */
 	settextcolor(12, 0);