add primitive vga terminal outputHEADmaster

3 files changed, 72 insertions, 40 deletions

diff --git a/boot/boot.asm b/boot/boot.asm
index eedde07..62f80f8 100644
--- a/boot/boot.asm
+++ b/boot/boot.asm
@@ -1,5 +1,7 @@
 format ELF64
 
+extrn kmain
+
 PML4_TABLE = 0x1000
 E820_MMAP  = 0xf000
 
@@ -9,7 +11,7 @@ include 'bios.inc'
 include 'page.inc'
 include 'segdesc.inc'
 
-section '.text.boot' executable
+section '.boot' executable writeable
 
 org 0x7c00
 use16
@@ -104,12 +106,17 @@ longmode:
 	xor ecx, ecx
 	xor edx, edx
 	xor edi, edi
+	xor esi, esi
 
 	; put stack at top of addressable memory
 	mov esp, 0x200000
 	mov ebp, esp
 
-	jmp 0x100000
+	; manually encoded 'jmp rel32', fasm throws an 'invalid use of symbol'
+	; error when generating code for a jmp to an external symbol after
+	; setting code origin with 'org' directive or a 'virtual at X' block.
+	db 0xe9
+	dd kmain-$-4
 
 align 4
 dw 0
diff --git a/kernel/main.c b/kernel/main.c
index 0633254..a4a905c 100644
--- a/kernel/main.c
+++ b/kernel/main.c
@@ -14,56 +14,72 @@ struct e820_entry {
 
 STATIC_ASSERT(sizeof(struct e820_entry) == 24, e820_entry);
 
-static uint64_t *
-memsetu64(uint64_t *const dst, const uint64_t c, const uint64_t n)
+struct vga_term {
+	uint16_t *buf;
+	uint16_t column;
+	uint16_t line;
+};
+
+static void
+vga_term_scroll(const struct vga_term *const term)
 {
-	for (uint64_t i = 0; i < n; ++i) dst[i] = c;
-	return dst;
+	for (int i = 0; i < VGA_HEIGHT-1; ++i)
+		for (int j = 0; j < VGA_WIDTH; ++j)
+			term->buf[i*VGA_WIDTH+j] = term->buf[(i+1)*VGA_WIDTH+j];
+	for (int i = 0; i < VGA_WIDTH; ++i)
+		term->buf[(VGA_HEIGHT-1)*VGA_WIDTH+i] = 0x0f20;
 }
 
-static uint16_t *
-print_hex(uint16_t *dst, uint64_t num)
+static void
+vga_term_newline(struct vga_term *const term)
 {
-	dst[0] = 0x0f00 | '0';
-	dst[1] = 0x0f00 | 'x';
+	if (term->line < VGA_HEIGHT-1)
+		++term->line;
+	else
+		vga_term_scroll(term);
 
-	dst += 2;
-
-	for (int i = 0; i < 16; ++i) {
-		uint16_t x = (num >> 60);
+	term->column = 0;
 
-		*(dst++) = 0x0f00 | (x < 0xa ? x+'0' : x+'a'-0xa);
+	return;
+}
 
-		num <<= 4;
+static void
+vga_term_putc(struct vga_term *const term, const char c, const uint8_t color)
+{
+	if (c == '\n') {
+		vga_term_newline(term);
+		return;
 	}
 
-	return dst;
+	if (term->column >= VGA_WIDTH)
+		vga_term_newline(term);
+
+	term->buf[term->line*VGA_WIDTH+(term->column++)] = (color<<8)|(c);
 }
 
-static uint16_t *
-puts(uint16_t *dst, const char *str)
+static void
+vga_term_puts(struct vga_term *const term, const char *const str, const uint8_t color)
 {
-	for (; *str; ++str, ++dst) *dst = 0x0f00|(*str);
-	return dst;
+	for (int i = 0; str[i]; ++i)
+		vga_term_putc(term, str[i], color);
 }
 
-static uint16_t *
-print_e820_table(uint16_t *dst, const struct e820_entry *const entries, const uint16_t count)
+static void
+vga_term_print_hex(struct vga_term *const term, uint64_t num, const uint8_t color)
 {
-	for (uint16_t i = 0; i < count; ++i, dst += VGA_WIDTH) {
-		uint16_t *cursor;
+	vga_term_putc(term, '0', color);
+	vga_term_putc(term, 'x', color);
 
-		cursor = print_hex(dst, entries[i].base);
+	for (int i = 0; i < 16; ++i) {
+		char c;
 
-		*(cursor++) = 0x0f00 | '-';
+		c = (num >> 60);
+		c = (c < 0xa) ? (c + '0') : (c + 'a' - 0xa);
 
-		cursor = print_hex(cursor, entries[i].base + entries[i].length - 1);
+		vga_term_putc(term, c, color);
 
-		++cursor;
-		cursor = puts(cursor, entries[i].type == 1 ? "available" : "reserved");
+		num <<= 4;
 	}
-
-	return dst;
 }
 
 void
@@ -71,16 +87,25 @@ kmain(void)
 {
 	vga_cursor_hide();
 
-	uint16_t *const vga_memory = (uint16_t *)0xb8000;
-	memsetu64((uint64_t *)vga_memory, 0x0f200f200f200f20, (VGA_WIDTH*VGA_HEIGHT*sizeof(uint16_t))/sizeof(uint64_t));
+	struct vga_term term = {(uint16_t *)0xb8000, 0, 0};
+
+	for (int i = 0; i < VGA_WIDTH*VGA_HEIGHT; ++i)
+		term.buf[i] = 0x0f20;
 
-	puts(vga_memory, "ProvidenceOS v0.1");
-	puts(vga_memory+VGA_WIDTH*2, "e820 memory map:");
+	vga_term_puts(&term, "ProvidenceOS v0.1\n\ne820 memory map:\n", 0x0f);
 
 	const uint16_t e820_size = *(uint16_t *)0xf000;
 	const struct e820_entry *const e820_mmap = (struct e820_entry *)0xf008;
 
-	print_e820_table(vga_memory+(VGA_WIDTH*3), e820_mmap, e820_size);
+	for (uint16_t i = 0; i < e820_size; ++i) {
+		vga_term_print_hex(&term, e820_mmap[i].base, 0x0f);
+		vga_term_putc(&term, '-', 0x0f);
+
+		vga_term_print_hex(&term, e820_mmap[i].base + e820_mmap[i].length - 1, 0x0f);
+		vga_term_putc(&term, ' ', 0x0f);
+
+		vga_term_puts(&term, e820_mmap[i].type == 1 ? "available\n" : "reserved\n", 0x0f);
+	}
 
 	halt();
 }
diff --git a/link.ld b/link.ld
index 11536c8..6721c00 100644
--- a/link.ld
+++ b/link.ld
@@ -6,15 +6,15 @@ KERNEL_VMA = 0x100000;
 SECTIONS {
 	. = 0x7c00;
 
-	.text.boot : {
-		boot/boot.o (.text.boot)
+	.boot : {
+		boot/boot.o (.boot)
 		_boot_end = .;
 	}
 
 	. = KERNEL_VMA;
 	.text : AT(_boot_end) {
-		*(.text.startup)
 		*(.text)
+		*(.text.*)
 		*(.rodata*)
 		. = ALIGN(0x1000);
 	}