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boot: move READBUF and READADDR_OFF/SEG to allow 8 KiB sector size

This commit is contained in:
E. C. Masloch 2024-02-06 22:01:22 +01:00 committed by Kenneth J Davis
parent 5cbe1ffcf0
commit 0776645017
1 changed files with 9 additions and 9 deletions
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18
boot/boot.asm
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@ -33,16 +33,16 @@
; |BOOTSEC| loader relocates itself here first thing,
; |RELOC. | before loading root directory/FAT/kernel file
; |-------| 1FE0h:7C00h = 27A00h (158 KiB)
; | gap |
; | gap | PARAMS live here
; |LBA PKT| LBA disk packet
; |-------| 1FE0h:7BC0h = 279C0h (158 KiB)
; | gap |
; | gap | READADDR_* live here
; |-------| 1FE0h:7BA0h = 279A0h (158 KiB)
; | STACK | below relocated loader, above sector buffer (size 2 KiB)
; | STACK | below relocated loader, above sector buffer (size 5.9 KiB)
; ...
; |-------|
; |SEC.BUF| sector buffer, used to avoid crossing 64 KiB DMA boundary
; |-------| 1FE0h:63A0h = 261A0h (152 KiB)
; |-------| 1FE0h:6400h = 26200h (152 KiB)
; |SEC.BUF| sector buffer, to avoid crossing 64 KiB DMA boundary (size 8 KiB)
; |-------| 1FE0h:4400h = 24200h (144 KiB)
; ...
; |-------| 1FE0h:4380h = 24182h (144 KiB)
; |CLUSTER| built from FAT, listing every cluster of the kernel file.
@ -155,9 +155,9 @@ Entry: jmp short real_start
%define LBA_SECTOR_32 word [LBA_PACKET+12]
%define LBA_SECTOR_48 word [LBA_PACKET+14]
%define READBUF 0x63A0 ; max 4KB buffer (min 2KB stack), == stacktop-0x1800
%define READADDR_OFF BP-0x60-0x1804 ; pointer within user buffer
%define READADDR_SEG BP-0x60-0x1802
%define READBUF 0x4400 ; max 8 KiB buffer
%define READADDR_OFF word BP-0x60 ; pointer within user buffer
%define READADDR_SEG word BP-0x60+2
%define PARAMS LBA_PACKET+0x10
;%define RootDirSecs PARAMS+0x0 ; # of sectors root dir uses