From d1444761a3c1fbecdc4f5f739226da6137033738 Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Fri, 17 Nov 2023 20:31:42 +0200
Subject: [PATCH] Bootloader: Clear screen, better memcpy

Clear screen before jumping to kernel. Memcpy now uses ebx as offset
register, so only one register has to updated every loop
---
 bootloader/boot.S |  9 +++++++--
 bootloader/elf.S  |  2 +-
 bootloader/ext2.S | 18 ++++++++++--------
 3 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/bootloader/boot.S b/bootloader/boot.S
index 4e12bbde..e5ae1f18 100644
--- a/bootloader/boot.S
+++ b/bootloader/boot.S
@@ -82,15 +82,20 @@ stage2_main:
 
 	call elf_read_kernel_to_memory
 
-	cli
+	# re-enter 80x25 text mode to clear screen
+	pushw %ax
+	movb $0x03, %al
+	movb $0x00, %ah
+	int $0x10
+	popw %ax
 
+	cli
 
 	# setup protected mode
 	movl %cr0, %ebx
 	orb $1, %bl
 	movl %ebx, %cr0
 
-
 	# jump to kernel in protected mode
 	ljmpl $0x18, $protected_mode
 
diff --git a/bootloader/elf.S b/bootloader/elf.S
index 059c4581..14d9ea4c 100644
--- a/bootloader/elf.S
+++ b/bootloader/elf.S
@@ -170,7 +170,7 @@ elf_read_kernel_to_memory:
 	andl $0x7FFFFFFF, %edi
 	movl (elf_program_header + p_filesz), %ecx
 
-	call print_hex32; call print_newline
+	#call print_hex32; call print_newline
 
 	call *%esi
 
diff --git a/bootloader/ext2.S b/bootloader/ext2.S
index 6937f266..c42e587d 100644
--- a/bootloader/ext2.S
+++ b/bootloader/ext2.S
@@ -409,13 +409,14 @@ ext2_inode_read_bytes:
 	addl %edx, %esi
 
 	# very dumb memcpy with 32 bit addresses
+	movl $0, %ebx
  .ext2_inode_read_bytes_memcpy_partial:
-	movb (%esi), %al
-	movb %al, (%edi)
-	incl %esi
-	incl %edi
+	movb (%esi, %ebx), %al
+	movb %al, (%edi, %ebx)
+	incl %ebx
 	decl %ecx
 	jnz .ext2_inode_read_bytes_memcpy_partial
+	addl %ebx, %edi
 
 	# check if all sectors are read
 	cmpl $0, 4(%esp)
@@ -441,13 +442,14 @@ ext2_inode_read_bytes:
 
 	# very dumb memcpy with 32 bit addresses
 	movl $ext2_block_buffer, %esi
+	movl $0, %ebx
  .ext2_inode_read_bytes_memcpy:
-	movb (%esi), %al
-	movb %al, (%edi)
-	incl %esi
-	incl %edi
+	movb (%esi, %ebx), %al
+	movb %al, (%edi, %ebx)
+	incl %ebx
 	decl %ecx
 	jnz .ext2_inode_read_bytes_memcpy
+	addl %ebx, %edi
 
 	# read next block if more sectors remaining
 	cmpl $0, 4(%esp)