Made it possible to load 8 sectors into ram
This commit is contained in:
Eric-Paul Ickhorn
parent
49230d4c72
commit
f5fe3a2172
3
build.sh
3
build.sh
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@ -8,4 +8,5 @@ cd stage_2
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./build.sh
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cd ../
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cat stage_1/stage_1.bin > nightloader.bin
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# cat stage_2/stage_2.bin >> nightloader.bin
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@ -1,3 +1,3 @@
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#!/bin/env bash
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qemu-system-x86_64 nightloader.bin
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@ -0,0 +1,4 @@
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; TODO: Read FAT32 filesystem and load raw binary frompath nightloader/stage_2.bin
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@ -0,0 +1,124 @@
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times 442 - ($-$$) db 0
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db "####"
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times 446 - ($-$$) db 0
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mbr_table:
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.part_1:
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db 0x80 ; bootable flag
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db 0, 2, 0 ; CHS - start-address (ordering: cylinder, sector, header)
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db 0x9d
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db 0, 16, 0 ; CHS - end-address (ordering: cylinder, sector, header)
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dd 2
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dd 16
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.part_2:
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db 0x00 ; bootable flag
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db 0, 0, 0 ; CHS - start-address (ordering: cylinder, sector, header)
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db 0x0
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db 0, 0, 0 ; CHS - end-address (ordering: cylinder, sector, header)
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dd 0
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dd 0
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.part_3:
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db 0x00 ; bootable flag
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db 0, 0, 0 ; CHS - start-address (ordering: cylinder, sector, header)
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db 0x00
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db 0, 0, 0 ; CHS - end-address (ordering: cylinder, sector, header)
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dd 0
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dd 0
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.part_4:
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db 0x00 ; bootable flag
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db 0, 0, 0 ; CHS - start-address (ordering: cylinder, sector, header)
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db 0x00
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db 0, 0, 0 ; CHS - end-address (ordering: cylinder, sector, header)
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dd 0
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dd 0
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.signature:
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db 0x55, 0xaa
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second_stage:
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;mov si, finish_text
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;mov dl, 36
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;mov dh, 12
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;mov cx, 8
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; set the video mode correctly
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xor ah, ah ; bios-function (set video mode)
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mov al, 3 ; video mode with 80x25 characters
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int 0x10
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.happiness:
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mov ah, 0x02 ; action: move cursor
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mov bh, 0 ; page
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mov dh, 1 ; row
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mov dl, 1 ; column
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int 0x10
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mov ah, 0x0a ; action: write character
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mov al, '$' ; character
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mov bh, 0 ; page
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mov cx, 13 ; count
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int 10h
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jmp .happiness
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.prolog:
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push di
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push cx
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push bx
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push ax
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xor di, di ; character index
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.printing_loop:
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.set_cursor_position:
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.write_character:
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push cx ; save len_buffer
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; get the current character
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mov bx, si
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add bx, di
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mov al, [bx]
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; al now contains the current character
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; set the other needed interrupt values
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mov ah, 0x0a ; wanted function (write character at cursor position)
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mov bh, 0 ; page number
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mov cx, 1 ; repetitions of character
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int 0x10 ; call bios basic draw functions
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pop cx ; restore len_buffer
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inc dl ; go to next column
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; go to a new line if needed
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cmp dl, 80
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jb .no_new_line_needed
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xor dl, dl
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inc dh ; increase column
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.no_new_line_needed:
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inc di ; go to next character
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; go further if the string-printing hasn't been finished
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cmp di, cx
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jb .printing_loop
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.epilog:
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jmp .epilog
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finish_text:
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db "-FINISH-"
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@ -1,210 +1,123 @@
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section .text
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org 0x7c00
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start:
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mov ax, 0
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mov ds, ax
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mov es, ax
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mov gs, ax
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mov fs, ax
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mov ax, 0x7e00
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mov ss, ax
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STAGE_1_CODE_MEMORY_ADDRESS equ 0x7c00
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STAGE_1_STACK_MEMORY_ADDRESS equ 0x07e0
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mov sp, 256
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NIGHTLOADER_PARTITION_TYPE equ 0x9d
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ORIGINAL_PARTITION_TABLE_OFFSET equ 446
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ORIGINAL_NUM_PARTITIONS_IN_TABLE equ 4
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ORIGINAL_PARTITION_ENTRY_SIZE equ 16
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BOOTABLE_BYTE_OFFSET equ 0
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CHS_START_SECTOR_ADDRESS_OFFSET equ 1
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PARTITION_TYPE_OFFSET equ 4
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CHS_END_SECTOR_ADDRESS equ 5
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FIRST_LBA_SECTOR_ADDR_OFFSET equ 8
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LAST_LBA_SECTOR_ADDR_OFFSET equ 12
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org STAGE_1_CODE_MEMORY_ADDRESS
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bits 16
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stage_0:
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mov bx, STAGE_1_STACK_MEMORY_ADDRESS
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mov ss, bx
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mov bx, 0x0800
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mov bp, 256
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mov sp, 256
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mov si, dx ; save the origin disk number
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mov bx, 0x0000
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mov ds, bx
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mov es, bx
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mov ax, 0x7c00
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add ax, 446
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; ax now points to the start of the partition table
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mov di, dx
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; set the video mode correctly
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xor ah, ah ; bios-function (set video mode)
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mov al, 3 ; video mode with 80x25 characters
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int 0x10
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xor di, di
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call initialize_video_mode
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.search_partition:
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mov bx, ax ; get the offset of the current entry
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add bx, 4 ; go to the offset of the partition type
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mov cl, [bx]
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cmp cl, 0x9d
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je .load_partition
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mov si, STAGE_1_CODE_MEMORY_ADDRESS
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add si, ORIGINAL_PARTITION_TABLE_OFFSET
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mov cx, 0 ; offset of the current entry from the partition table start
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inc di
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; leave and print debug message if the last partition entry
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; did not provide the wanted bootloader - partition
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cmp di, 4
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je .no_boot_partition
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add ax, 16
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jmp .search_partition
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.search_loop:
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mov bx, si
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add bx, cx
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add bx, PARTITION_TYPE_OFFSET
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mov al, [bx]
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cmp al, NIGHTLOADER_PARTITION_TYPE
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je .load_partition;
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; go to the next entry
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add cx, ORIGINAL_PARTITION_ENTRY_SIZE
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; check if there are more entries
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cmp dx, ORIGINAL_NUM_PARTITIONS_IN_TABLE * ORIGINAL_PARTITION_ENTRY_SIZE
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jb .search_loop
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jmp .no_boot_partition
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.load_partition:
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; ax is the start of the bootloader's partition entry in the mbr
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; read the chs-entry and push it onto the stack
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mov si, cx ; address of the partition table entry of the nightloader-partition
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; head
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xor dx, dx
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mov bx, ax
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add bx, 1
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mov dl, [bx]
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push dx
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; cylinder
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xor dx, dx
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mov bx, ax
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add bx, 3
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mov dh, [bx]
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mov bx, ax
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add bx, 2
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mov dl, [bx]
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shr dx, 6
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push dx
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; sector
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xor dx, dx
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mov bx, ax
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add bx, 2
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mov dl, [bx]
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and dl, 0b00111111
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push dx
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; push the partition's length
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mov bx, ax
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add bx, 12
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mov dx, [bx]
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push dx ; lower part
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mov bx, ax
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add bx, 14
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mov dx, [bx]
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push dx ; higher part
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; load it all and read from disk
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mov bx, sp
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add bx, 4
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mov al, [bx] ; sector-count
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add bx, 2
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mov cl, [bx] ; start-sector
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add bx, 2
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mov ch, [bx] ; start-cylinder
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mov dx, si ; drive
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; TODO: Make this more flexible; that's urgent.
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mov ah, 0x02 ; action (read from disk)
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mov al, 8 ; num_sectors
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mov ch, 0 ; cylinder
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mov cl, 2 ; sector (starts at 1, max.: 63)
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mov dx, di ; storage device id
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mov dh, 0 ; head
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mov bx, 0x0800
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mov es, bx ; output segment
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mov es, bx ; read destination segment
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mov bx, 0x0000 ; read destination address
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int 0x13
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mov bx, sp
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add bx, 8
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mov dh, [bx] ; start-head
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call .write_hex
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mov cl, 2
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mov ah, 0x02
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mov al, 1
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mov bx, 0x0000 ; output address in es - segment
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int 13h
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mov cx, 8
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mov si, 0x8000
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mov cx, 8
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mov dh, 12
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mov dl, 32
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mov dl, 36
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call print_string
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jmp .keepalive
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; jmp .wait
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jmp 0x0800:0x0000
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.no_boot_partition:
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mov cx, LEN_TEXT_NO_BOOT_PARTITION
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mov si, error_texts.no_boot_partition
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mov si, errors.no_boot_partition
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mov cx, 30
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mov dl, 25
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mov dh, 12
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mov dl, 32
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call print_string
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.keepalive:
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jmp .keepalive
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.wait:
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cli
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hlt
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.write_hex:
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push bx
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push cx
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mov bx, error_texts.hextab
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and cx, 0x0f
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add bx, cx
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mov cl, [bx]
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mov bx, error_texts.hexbuf
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inc bx
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mov [bx], cl
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mov bx, error_texts.hextab
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and cx, 0xf0
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shr cx, 4
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add bx, cx
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mov cl, [bx]
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mov bx, error_texts.hexbuf
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mov [bx], cl
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mov cx, 2
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mov si, error_texts.hexbuf
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mov dh, 12
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mov dl, 32
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call print_string
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pop cx
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pop bx
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ret
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; %include "exfat.asm"
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%include "gdt.asm"
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%include "utility.asm"
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LEN_TEXT_NO_BOOT_PARTITION equ 17
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error_texts:
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MESSAGE_LENGTH_NO_BOOT_PARTITION equ 30
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errors:
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.no_boot_partition:
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;db "NO_BOOT_PARTITION"
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.hextab:
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db "NO NIGHTLOADER-PARTITION FOUND"
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.hex:
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db "0123456789abcdef"
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.hexbuf:
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resb 4
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times 446 - ($-$$) db 0
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db 0x80
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db 0, 2, 0
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db 0x9d
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db 0, 3, 0
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dd 1
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dd 1
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times 510 - ($-$$) db 0
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db 0x55
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db 0xAA
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db "################"
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%include "utility.asm"
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%include "fat32.asm"
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%include "partition_table.asm"
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@ -1,22 +1,4 @@
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section .text
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initialize_video_mode:
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.prolog:
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push ax
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; set the video mode correctly
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xor ah, ah ; bios-function (set video mode)
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mov al, 3 ; video mode with 80x25 characters
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int 0x10
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.epilog:
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pop ax
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ret
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; cx: len_buffer
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; si: buffer
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; dl: start_x NOTE: Will contain the end of the text on-screen
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@ -82,189 +64,3 @@ print_string:
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pop di
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ret
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; ds: source
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; es: destination
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; dx: len_to_copy
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mem_copy:
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push ax
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push bx
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push cx
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push dx
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xor cx, cx
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mov di, dx
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; ax: first region's value
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; bx: address at index
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; cx: byte_index
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; dx: second region's value
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.loop:
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; retrieve the source byte at the current index
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mov bx, cx
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mov dx, [bx]
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; swap the two segments
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; here, ax and bx are used differently.
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mov ax, es
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mov bx, ds
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mov ds, ax
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mov es, bx
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mov [bx], cx
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; swap the two segments back
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mov ax, es
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mov bx, ds
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mov ds, ax
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mov es, bx
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inc cx
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; if the end has NOT been reached
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cmp cx, di
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jb .loop ; => continue
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ret
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; ds: region_1
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; es: region_2
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; dx: len_regions
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; ax: result
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mem_equals:
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push bx
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push cx
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push dx
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push di
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xor cx, cx
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mov di, dx
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; ax: first region's value
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; bx: address at index
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; cx: byte_index
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; dx: second region's value
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.loop:
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mov bx, cx
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mov dx, [bx]
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; swap the two segments
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; here, ax and bx are used differently.
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mov ax, es
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mov bx, ds
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mov ds, ax
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mov es, bx
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mov bx, cx
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mov ax, [bx]
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cmp ax, dx
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; swap the two segments back
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mov ax, es
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mov bx, ds
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mov ds, ax
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mov es, bx
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; jump accordingly to the comparison above
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jne .not_equal
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inc cx
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cmp cx, di ; if the loop needs to continue
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jb .loop ; (if the end is NOT reached yet)
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; it goes here if the two regions are completely equal
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pop di
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pop dx
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pop cx
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pop bx
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mov ax, 1
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ret
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.not_equal:
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pop di
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pop dx
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pop cx
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pop bx
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mov ax, 0
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ret
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; ax: start_sector (upper)
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; bl: start_sector (lower)
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; cx: wanted_sector_count
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; dh: drive
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; si: buffer_address (upper)
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; di: buffer_address (lower)
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load_sectors:
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; INNER WORKING:
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;
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; This function first checks if it needs to load sectors going over
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; a cylinder boundary and loads to that cylinder boundary first continuing
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; in 63-sector - parts after that until the last, < 63-sectors part is read.
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;
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; This is done because some systems don't like reading over the boundaries
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; between the cylinders.
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;
|
||||
; The actual part loading the data is in .read_from_disk, it's no different
|
||||
; from the first read to the other reads. It just gets different arguments
|
||||
; from 1).load_first_sectors, and 2) .load_further_sectors
|
||||
;
|
||||
|
||||
.prolog:
|
||||
push ax
|
||||
push bx
|
||||
push cx
|
||||
push dx
|
||||
push si
|
||||
xor si, si ; current sector index
|
||||
|
||||
.load_first_sectors:
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
; ah: EMPTY
|
||||
; al: num_sectors_to_read
|
||||
; bx: EMPTY
|
||||
; ch: cylinder
|
||||
; cl: sector
|
||||
; dh: head
|
||||
; dl: drive
|
||||
.read_from_disk:
|
||||
|
||||
; set es:bx to the address in bytes to which the output should be written.
|
||||
|
||||
mov bx, si
|
||||
shr bx, 9
|
||||
|
||||
|
||||
|
||||
|
||||
mov ah, 0x02
|
||||
int 0x13
|
||||
|
||||
|
||||
|
||||
.load_further_sectors:
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
.epilog:
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue