Elaina Claus
8e05e071e8
files that actually include code should be in .nasm files defines/macros/non-code should be in .inc files
110 lines
3.2 KiB
NASM
110 lines
3.2 KiB
NASM
; Copyright (c) 2024 Elaina Claus
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;
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; Permission is hereby granted, free of charge, to any person obtaining a copy
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; of this software and associated documentation files (the "Software"), to deal
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; in the Software without restriction, including without limitation the rights
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; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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; copies of the Software, and to permit persons to whom the Software is
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; furnished to do so, subject to the following conditions:
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;
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; The above copyright notice and this permission notice shall be included in all
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; copies or substantial portions of the Software.
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;
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; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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; LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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; SOFTWARE.
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%ifndef __INC_EXT_READ
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;Offset Size Description
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; 0 1 size of packet (16 bytes)
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; 1 1 always 0
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; 2 2 number of sectors to transfer (max 127 on some BIOSes)
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; 4 4 transfer buffer (0xFFFF:0xFFFF)
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; 8 4 lower 32-bits of starting 48-bit LBA
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; 12 4 upper 32-bits of starting 48-bit LBA
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; needs to be aligned to a uint32_t
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struc LBAPkt_t
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.size resb 1
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.res0 resb 1
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.xfer_size resw 1
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.offset resw 1
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.segment resw 1
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.lower_lba resd 1
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.upper_lba resd 1
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endstruc
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; Wrapper for AH=0x42 INT13h (Extended Read)
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;
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; BIOS call details
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; AH = 42h
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; DL = drive number
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; DS:SI -> disk address packet
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;
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; Return:
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; CF clear if successful
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; AH = 00h
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; CF set on error
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; AH = error code
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; disk address packet's block count field set to number of blocks
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; successfully transferred
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;
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;
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; uint8_t read_stage2_raw(uint16_t buf_segment, uint16_t buf_offset,
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; uint32_t lba,
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; uint16_t count, uint16_t drive_num)
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ALIGN 4, db 0x90
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read_disk_raw:
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__CDECL16_ENTRY
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.func:
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mov ax, 0x10
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push ax ; len = 16 bytes
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xor ax, ax
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push ax ; val = 0
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mov ax, lba_packet
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push ax ; dest = lba_packet address
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call kmemset
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add sp, 0x06
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mov byte [lba_packet + LBAPkt_t.size], 0x10
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mov ax, [bp + 12]
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mov word [lba_packet + LBAPkt_t.xfer_size], ax
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mov eax, [bp + 8]
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mov dword [lba_packet + LBAPkt_t.lower_lba], eax
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mov ax, [bp + 6]
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mov word [lba_packet + LBAPkt_t.offset], ax
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mov ax, [bp + 4]
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mov word [lba_packet + LBAPkt_t.segment], ax
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mov si, lba_packet
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mov ah, 0x42
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;BUG: still working on getting this passed down correctly, going to hard set it for now.
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movzx dx, byte [bp + 14]
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and dx, 0x00ff
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;xor dl, dl
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;mov dl, 0x80
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int 0x13
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jnc .endf
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%ifdef __STEVIA_MBR
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ERROR MBR_ERROR_DISK_READ_ERR
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%elifdef __STEVIA_VBR
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ERROR VBR_ERROR_DISK_READ_ERR
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%else
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ERROR STAGE2_MBR_DISK_READ_ERROR
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%endif
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.endf:
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__CDECL16_EXIT
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ret
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%endif
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%define __INC_EXT_READ |