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Fix hdd booting using bpb struc

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This commit is contained in:
Nero 2020-09-19 08:22:50 +00:00
parent 1d64c2364d
commit 8ed9fe7465
2 changed files with 11 additions and 20 deletions
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12
boot/mbr.asm
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@ -10,7 +10,7 @@
%include "inc/bpb.asm"
%define bpb bs+0x0B
%define params bs+0x0B
cpu 8086
org 0x0600
@ -72,11 +72,11 @@ main: ; find active partition
; FAT bpb has "bytes per sector" at this place
; we support only 512 byte sectors anyways
cmp word [bpb+bpb_ss], 512
cmp word [params+bpb.sectorsize], 512
jne chain
; Media descriptor byte is never smaller than 0xF0
cmp byte [bpb+bpb_md], 0xF0
cmp byte [params+bpb.mediadesc], 0xF0
jc chain
; ask BIOS what our disk geometry is
@ -92,17 +92,17 @@ main: ; find active partition
; update sectors per track
xor ax, ax
mov al, cl
mov [bpb+bpb_spt], ax
mov [params+bpb.tracksectors], ax
; update number of sides
xor ax, ax
mov al, dh
mov [bpb+bpb_nos], ax
mov [params+bpb.heads], ax
; update partition offset
push si
add si, 0x08
mov di, bpb+bpb_po
mov di, params+bpb.sectoroffset
movsw
movsw
pop si