Many fixes and improvements to the BIOS Extension ROM. (#33)
* Revert "Uploaded_2_9_2025"
This reverts commit ec79bbdbc9.
* Fixing DEBUG_IO builds.
* Make the IO port base a define.
* Fix CPU test to properly handle 808x vs V20.
* Improve timeout management logic.
* Improve SD Card initialization logic.
* Implement INT18h bootstrapping.
* Implementing a different test for processor type.
* Allow use with another fixed drive (eg: ESDI drive).
* Allow swapping driver ID between the BIOS disk and XTMax.
* Fix address of the ROM segment.
* Fixing missing STI at the top of the handler.
* Major rework of IO to use MOVSW.
* More code reorg and auto-detecting second drive.
* Update XTSD to use MOVSW.
* Add diagnostics program.
* Workaround for MS-DOS strange handling of interrupts.
* Use a lookup table for the memory map.
* Make the BootROM relocatable.
* Some more refactor of the Teensy code.
This commit is contained in:
Matthieu Bucchianeri
committed by
GitHub
GitHub
parent
ec79bbdbc9
commit
fe8385da08
@@ -11,14 +11,31 @@ cpu 8086 ; ensure we remain compatible with 8086
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;%define DEBUG_IO
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;%define EXTRA_DEBUG
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%define FIXED_DISK_0 (0)
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%define FIXED_DISK_1 (1)
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;
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; The base I/O port for the XTMAX SD Card.
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;
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%define XTMAX_IO_BASE (0x280)
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%define REG_DATA (XTMAX_IO_BASE+0)
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%define REG_CS (XTMAX_IO_BASE+1) ; write-only
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%define REG_CONFIG (XTMAX_IO_BASE+1) ; read-only
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%define REG_SCRATCH_0 (XTMAX_IO_BASE+2) ; fixed disk id
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%define REG_SCRATCH_1 (XTMAX_IO_BASE+3) ; BIOS INT13h segment
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%define REG_SCRATCH_2 (XTMAX_IO_BASE+4) ; BIOS INT13h segment
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%define REG_SCRATCH_3 (XTMAX_IO_BASE+5) ; BIOS INT13h offset
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%define REG_SCRATCH_4 (XTMAX_IO_BASE+6) ; BIOS INT13h offset
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%define REG_TIMEOUT (XTMAX_IO_BASE+7)
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;
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; Whether we will emulate the 1st or 2nd disk.
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; Whether we will try/force using our own bootstrap code instead of falling back to BASIC.
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;
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%define DISK_NUMBER FIXED_DISK_0
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%define USE_BOOTSTRAP
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;%define FORCE_OWN_BOOTSTRAP
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;
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; Whether we are going to rename the BIOS's 1st disk to be the second disk.
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; This is useful to allow booting from the second disk.
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;
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;%define TAKE_OVER_FIXED_DISK_0
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;
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; The properties of our emulated disk.
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@@ -30,22 +47,26 @@ cpu 8086 ; ensure we remain compatible with 8086
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%define NUM_SECTORS (NUM_HEADS * (NUM_CYLINDERS - 1) * SECTORS_PER_TRACK)
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%if NUM_HEADS > 255
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%error NUM_HEADS is too large
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%error NUM_HEADS_ is too large
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%endif
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%if NUM_HEADS > 16
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%warning NUM_HEADS_ above 16 can cause compatibility issues
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%endif
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%if SECTORS_PER_TRACK > 63
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%error SECTORS_PER_TRACK is too large
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%error SECTORS_PER_TRACK_ is too large
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%endif
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%if NUM_CYLINDERS > 1024
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%error NUM_CYLINDERS is too large
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%error NUM_CYLINDERS_ is too large
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%endif
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beginning_of_rom:
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%ifndef AS_COM_PROGRAM
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;
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; BIOS will look for the AA55 signature between C8000-DFFFF in 2KB increments.
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; We choose an address in that range.
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;
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%define ROM_SEGMENT (0xc000)
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org (ROM_SEGMENT << 4 | 0xe000)
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%define ROM_SEGMENT (0xce00)
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org 0
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dw 0AA55h ; signature
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db 4 ; size in blocks of 512 bytes
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@@ -61,6 +82,7 @@ entry:
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%ifndef AS_COM_PROGRAM
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push es
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push ax
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push cx
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push dx
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cli
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%endif
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@@ -68,6 +90,17 @@ entry:
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mov ax, welcome_msg
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call print_string
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mov ax, rom_base_msg
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call print_string
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mov ax, cs
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call print_hex
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mov ax, colon
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call print_string
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mov ax, beginning_of_rom
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call print_hex
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mov ax, newline
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call print_string
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;
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; Initialize the SD Card.
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;
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@@ -76,76 +109,66 @@ entry:
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jc .skip
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%endif
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;
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; Detecting 80186-compatible so we can use REP INSW/OUTSW.
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; Based on https://www.rcollins.org/ftp/source/cpuid/cpuid.asm
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;
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.cpuid:
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push sp
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pop ax
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cmp ax, sp ; if below 80286, these values will differ
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jz .support_string_io ; nope, 80286 or higher
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mov ax, ds:[0xffff] ; get original data
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mov word ds:[0xffff], 0xaaaa ; write signature at test location
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cmp byte ds:[0], 0xaa ; 8086 will write the 2nd byte at offset 0
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mov ds:[0xffff], ax
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je .test_v20
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jmp .support_string_io ; we have an 80186/80188
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.test_v20:
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push ax ; save results
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xor al, al ; force ZF
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mov al, 0x40 ; multiplicand
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mul al ; V20 doesn't affect ZF
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pop ax ; restore results
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jz .support_string_io ; we have an V20
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xor dl, dl
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jmp .store_string_io
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.support_string_io:
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mov dl, 1
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mov ax, string_io_msg
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call print_string
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.store_string_io:
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mov ax, 0x283 ; scratch register 0
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xchg ax, dx
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out dx, al ; save capability
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%ifndef AS_COM_PROGRAM
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;
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; Install our BIOS INT13h hook into the interrupt vector table.
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;
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.install_13h_vector:
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mov ax, old_13h_msg
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call print_string
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xor ax, ax ; INT vector segment
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mov es, ax
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mov ax, es:[0x13*4+2]
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mov dx, 0x284 ; scratch register 1-2
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mov dx, REG_SCRATCH_1
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out dx, ax ; save segment
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call print_hex
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mov ax, colon
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call print_string
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mov ax, es:[0x13*4]
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mov dx, 0x286 ; scratch register 3-4
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mov dx, REG_SCRATCH_3
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out dx, ax ; save offset
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call print_hex
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mov ax, newline
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call print_string
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mov ax, new_13h_msg
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call print_string
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mov ax, ROM_SEGMENT
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mov ax, cs
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mov es:[0x13*4+2], ax ; store segment
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call print_hex
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mov ax, colon
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call print_string
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mov ax, int13h_entry
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mov es:[0x13*4], ax ; store offset
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;
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; Move fixed disk 0 to fixed disk 1.
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;
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%ifdef TAKE_OVER_FIXED_DISK_0
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call swap_fixed_disk_parameters_tables
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%endif
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;
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; Determine our fixed disk ID.
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;
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.identify_fixed_disk:
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mov ax, disk_id_msg
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call print_string
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mov ax, 0x40 ; BIOS data area
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mov es, ax
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%ifndef TAKE_OVER_FIXED_DISK_0
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mov al, es:[0x75] ; HDNUM
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add al, 0x80
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%else
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mov al, 0x80
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%endif
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mov dx, REG_SCRATCH_0 ; save fixed disk id
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out dx, al
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push ax
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call print_hex
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mov ax, newline
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call print_string
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%if !(%isdef(USE_BOOTSTRAP) && %isdef(FORCE_OWN_BOOTSTRAP))
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.update_bda:
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;
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; Increment the number of fixed disks in the BIOS Data Area.
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;
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mov ax, num_drives_msg
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call print_string
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inc byte es:[0x75] ; HDNUM
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mov al, es:[0x75]
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xor ah, ah
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call print_hex
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mov ax, newline
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call print_string
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%endif
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pop ax
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;
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; Install our fixed disk parameter table.
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@@ -153,30 +176,37 @@ entry:
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; For the 2nd disk, it is stored in the interrupt vector table, at vector 46h.
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;
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.install_fixed_disk_parameters_table:
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mov ax, new_fdpt_msg
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call print_string
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mov ax, ROM_SEGMENT
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mov es:[(0x41+DISK_NUMBER*5)*4+2], ax ; store segment
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call print_hex
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mov ax, colon
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call print_string
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xor cx, cx ; INT vector segment
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mov es, cx
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cmp al, 0x80
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jne .second_disk
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mov ax, cs
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mov es:[0x41*4+2], ax ; store segment
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mov ax, fixed_disk_parameters_table
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mov es:[(0x41+DISK_NUMBER*5)*4], ax ; store offset
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call print_hex
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mov ax, newline
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call print_string
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mov es:[0x41*4+0], ax ; store offset
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jmp .end_fdpt
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.second_disk:
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mov ax, cs
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mov es:[0x46*4+2], ax ; store segment
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mov ax, fixed_disk_parameters_table
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mov es:[0x46*4+0], ax ; store offset
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.end_fdpt:
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%ifdef USE_BOOTSTRAP
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;
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; Increment the number of fixed disks in the BIOS Data Area.
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; Install our BIOS INT18h hook into the interrupt vector table.
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;
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mov ax, 0x40 ; BIOS data area
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mov es, ax
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inc byte es:[0x75] ; HDNUM
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.install_18h_vector:
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mov ax, cs
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mov es:[0x18*4+2], ax ; store segment
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mov ax, int18h_entry
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mov es:[0x18*4], ax ; store offset
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%endif
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.skip:
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sti
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pop dx
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pop cx
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pop ax
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pop es
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retf
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@@ -210,52 +240,94 @@ entry:
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;
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int13h_entry:
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%ifdef EXTRA_DEBUG
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push TEMP0
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mov TEMP0, sp
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mov TEMP0, [TEMP0+6] ; grab the flags for iret
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push TEMP0
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popf
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pop TEMP0
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call dump_regs
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%endif
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sti
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push TEMP0
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push TEMP1
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cmp dl, 0x80+DISK_NUMBER ; is this our drive?
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push ax
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push dx
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mov dx, REG_SCRATCH_0
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in al, dx
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pop dx
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cmp dl, al ; is this our drive?
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pop ax
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je .check_function
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;
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; This is not an operation for the SD Card. Forward to the BIOS INT 13h handler.
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;
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.forward_to_bios:
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%ifdef TAKE_OVER_FIXED_DISK_0
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cmp dl, 0x81 ; is this the other fixed drive?
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jne .no_fixed_disk_take_over
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mov dl, 0x80
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call swap_fixed_disk_parameters_tables
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.no_fixed_disk_take_over:
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%endif
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mov TEMP0, ax ; save ax
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mov TEMP1, dx ; save dx
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pushf ; setup for iret from INT 13h handler
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push cs ; setup for iret from INT 13h handler
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mov ax, .return_common
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mov ax, .return_from_int13h
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push ax ; setup for iret from INT 13h handler
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.simulate_int13h:
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;
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; Simulate INT 13h with the original vector.
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;
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pushf ; setup for iret below
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mov dx, 0x284 ; scratch register 1-2
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mov dx, REG_SCRATCH_1
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%ifndef AS_COM_PROGRAM
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in ax, dx
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%else
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mov ax, cs
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%endif
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push ax ; setup for iret below
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mov dx, 0x286 ; scratch register 3-4
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push ax ; setup for retf below
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mov dx, REG_SCRATCH_3
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%ifndef AS_COM_PROGRAM
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in ax, dx
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%else
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mov ax, fake_int13h_entry
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%endif
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push ax ; setup for iret below
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push ax ; setup for retf below
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mov ax, TEMP0 ; restore ax
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mov dx, TEMP1 ; restore dx
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iret ; call the INT 13h handler
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; will return at .return_common
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cli ; INT inhibits interrupts
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retf ; call the INT 13h handler
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.return_from_int13h:
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sti ; just in case
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pushf
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push ax
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mov ax, TEMP1 ; original dx
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cmp al, 0x80 ; is fixed fixed?
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jb .skip_update_hdnum
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%ifdef TAKE_OVER_FIXED_DISK_0
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mov dl, 0x81
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call swap_fixed_disk_parameters_tables
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%endif
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mov ax, TEMP0 ; original ax
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cmp ah, 0x08 ; is read parameters?
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jne .skip_update_hdnum
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push es
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mov ax, 0x40 ; BIOS data area
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mov es, ax
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mov dl, es:[0x75] ; HDNUM
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pop es
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.skip_update_hdnum:
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pop ax
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popf
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jmp .return_common
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;
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; This is an operation for the SD Card. Use our own INT 13h logic.
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;
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.check_function:
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cmp ah, 0x15 ; is valid function?
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cmp ah, 0x19 ; is valid function?
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jle .prepare_call
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call func_unsupported
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jmp .update_bda
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@@ -319,6 +391,7 @@ int13h_entry:
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.return_with_flags:
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pop TEMP1
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pop TEMP0
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sti ; workaround - MS-DOS does not properly propagate IF
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%ifdef EXTRA_DEBUG
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call dump_regs
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%endif
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@@ -350,6 +423,10 @@ func_table:
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dw func_unsupported ; diagnostics
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dw func_10_is_ready ; diagnostics
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dw func_15_read_size
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dw func_unsupported ; detect_change
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dw func_unsupported ; set_media_type
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dw func_unsupported ; set_media_type
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dw func_10_is_ready ; park_heads
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func_unsupported:
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%ifdef DEBUG
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@@ -440,6 +517,7 @@ func_02_read_sector:
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jc error_sector_not_found
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; TODO: (robustness) check buffer boundaries
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.setup:
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push ds
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push bx
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push cx
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push dx
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@@ -447,9 +525,11 @@ func_02_read_sector:
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push ax
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mov cx, ax ; number of sectors to read
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xor ch, ch
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mov di, bx ; setup use of stosw
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mov ax, cs
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mov ds, ax
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mov di, bx ; setup use of movsw
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.assert_cs:
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mov dx, 0x282 ; chip select port
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mov dx, REG_CS
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mov al, 0 ; assert chip select
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out dx, al
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.cmd17:
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@@ -468,46 +548,40 @@ func_02_read_sector:
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mov ax, wait_msg
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call print_string
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%endif
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mov dx, 0x280 ; data port
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mov cx, 50000 ; timeout (50ms)
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jmp .receive_token_no_delay
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mov dx, REG_TIMEOUT
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mov al, 10 ; 100 ms
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out dx, al
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.receive_token:
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call delay_us
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.receive_token_no_delay:
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mov dx, REG_DATA
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in al, dx
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cmp al, 0xfe
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loopne .receive_token
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jne .error
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je .got_token
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mov dx, REG_TIMEOUT
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in al, dx
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test al, al
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jnz .error
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jmp .receive_token
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.got_token:
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%ifdef DEBUG_IO
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mov ax, sd_token_msg
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call print_string
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%endif
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mov cx, 256 ; block size (in words)
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push dx
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mov dx, 0x283 ; scratch register 0
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in al, dx
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pop dx
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test al, al ; supports insw?
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push si
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mov si, end_of_rom ; virtual buffer
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cld
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jz .receive_block
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.receive_block_fast:
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cpu 186
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rep insw
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cpu 8086
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jmp .receive_crc
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.receive_block:
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in ax, dx
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stosw
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loop .receive_block
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rep movsw
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.receive_crc:
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in ax, dx ; discard CRC
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lodsw ; discard CRC
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pop si
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add TEMP_LO, 1 ; next block
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adc TEMP_HI, 0 ; carry
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pop cx ; number of sectors left to read
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loop .cmd17
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.success:
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.deassert_cs1:
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mov dx, 0x282 ; chip select port
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mov dx, REG_CS
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mov al, 1 ; deassert chip select
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out dx, al
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.return1:
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@@ -516,10 +590,11 @@ cpu 8086
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pop dx
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pop cx
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pop bx
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pop ds
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jmp succeeded
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.error:
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.deassert_cs2:
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mov dx, 0x282 ; chip select port
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mov dx, REG_CS
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mov al, 1 ; deassert chip select
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out dx, al
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||||
.return2:
|
||||
@@ -530,6 +605,7 @@ cpu 8086
|
||||
pop dx
|
||||
pop cx
|
||||
pop bx
|
||||
pop ds
|
||||
jmp error_drive_not_ready
|
||||
|
||||
;
|
||||
@@ -576,9 +652,11 @@ func_03_write_sector:
|
||||
xor ch, ch
|
||||
mov di, bx ; destination address
|
||||
mov ax, es
|
||||
mov ds, ax
|
||||
mov ds, ax ; save es and setup for movsw
|
||||
mov ax, cs
|
||||
mov es, ax
|
||||
.assert_cs:
|
||||
mov dx, 0x282 ; chip select port
|
||||
mov dx, REG_CS
|
||||
mov al, 0 ; assert chip select
|
||||
out dx, al
|
||||
.cmd24:
|
||||
@@ -593,41 +671,36 @@ func_03_write_sector:
|
||||
mov cl, 0x58 ; CMD24
|
||||
call send_sd_read_write_cmd
|
||||
jc .error
|
||||
mov dx, 0x280 ; data port
|
||||
mov dx, REG_DATA
|
||||
mov al, 0xfe ; send token
|
||||
out dx, al
|
||||
mov cx, 256 ; block size (in words)
|
||||
xchg di, si ; save si (aka TEMP1)
|
||||
push dx
|
||||
mov dx, 0x283 ; scratch register 0
|
||||
in al, dx
|
||||
pop dx
|
||||
test al, al ; supports outsw?
|
||||
push si ; save si (aka TEMP1)
|
||||
mov si, di
|
||||
mov di, end_of_rom ; virtual buffer
|
||||
cld
|
||||
jz .send_block
|
||||
.send_block_fast:
|
||||
cpu 186
|
||||
rep outsw
|
||||
cpu 8086
|
||||
jmp .end_send_block
|
||||
.send_block:
|
||||
lodsw
|
||||
out dx, ax
|
||||
loop .send_block
|
||||
.end_send_block:
|
||||
xchg si, di ; restore si (aka TEMP1)
|
||||
rep movsw
|
||||
mov di, si
|
||||
pop si ; restore si (aka TEMP1)
|
||||
%ifdef DEBUG_IO
|
||||
mov ax, wait_msg
|
||||
call print_string
|
||||
%endif
|
||||
mov cx, 50000 ; timeout (50ms)
|
||||
jmp .receive_status_no_delay
|
||||
mov dx, REG_TIMEOUT
|
||||
mov al, 25 ; 250 ms
|
||||
out dx, al
|
||||
.receive_status:
|
||||
call delay_us
|
||||
.receive_status_no_delay:
|
||||
mov dx, REG_DATA
|
||||
in al, dx
|
||||
cmp al, 0xff
|
||||
loope .receive_status
|
||||
jne .got_status
|
||||
mov dx, REG_TIMEOUT
|
||||
in al, dx
|
||||
test al, al
|
||||
jnz .error
|
||||
jmp .receive_status
|
||||
.got_status:
|
||||
%ifdef DEBUG_IO
|
||||
push ax
|
||||
mov ax, sd_status_msg
|
||||
@@ -647,15 +720,20 @@ cpu 8086
|
||||
mov ax, wait_msg
|
||||
call print_string
|
||||
%endif
|
||||
mov cx, 50000 ; timeout (50ms)
|
||||
jmp .receive_finish_no_delay
|
||||
mov dx, REG_TIMEOUT
|
||||
mov al, 25 ; 250 ms
|
||||
out dx, al
|
||||
.receive_finish:
|
||||
call delay_us
|
||||
.receive_finish_no_delay:
|
||||
mov dx, REG_DATA
|
||||
in al, dx
|
||||
test al, al
|
||||
loope .receive_finish
|
||||
jz .error
|
||||
jnz .got_finish
|
||||
mov dx, REG_TIMEOUT
|
||||
in al, dx
|
||||
test al, al
|
||||
jnz .error
|
||||
jmp .receive_finish
|
||||
.got_finish:
|
||||
%ifdef DEBUG_IO
|
||||
mov ax, sd_idle_msg
|
||||
call print_string
|
||||
@@ -663,13 +741,20 @@ cpu 8086
|
||||
add TEMP_LO, 1 ; next block
|
||||
adc TEMP_HI, 0 ; carry
|
||||
pop cx ; number of sectors left to write
|
||||
%ifndef DEBUG_IO
|
||||
loop .cmd24
|
||||
%else
|
||||
dec cx
|
||||
jnz .cmd24
|
||||
%endif
|
||||
.success:
|
||||
.deassert_cs1:
|
||||
mov dx, 0x282 ; chip select port
|
||||
mov dx, REG_CS
|
||||
mov al, 1 ; deassert chip select
|
||||
out dx, al
|
||||
.return1:
|
||||
mov ax, ds
|
||||
mov es, ax ; restore es
|
||||
pop ax
|
||||
pop di
|
||||
pop dx
|
||||
@@ -679,11 +764,13 @@ cpu 8086
|
||||
jmp succeeded
|
||||
.error:
|
||||
.deassert_cs2:
|
||||
mov dx, 0x282 ; chip select port
|
||||
mov dx, REG_CS
|
||||
mov al, 1 ; deassert chip select
|
||||
out dx, al
|
||||
.return2:
|
||||
pop cx ; number of sectors not written successfully
|
||||
mov ax, ds
|
||||
mov es, ax ; restore es
|
||||
pop ax
|
||||
sub al, cl ; number of sectors written successfully
|
||||
pop di
|
||||
@@ -749,6 +836,7 @@ func_08_read_params:
|
||||
mov es, ax
|
||||
mov dl, es:[0x75] ; HDNUM
|
||||
pop es
|
||||
|
||||
; the last cylinder is reserved on fixed disks
|
||||
mov ch, ((NUM_CYLINDERS - 2) & 0xff)
|
||||
mov cl, (((NUM_CYLINDERS - 2) & 0x300) >> 2) | SECTORS_PER_TRACK
|
||||
@@ -836,10 +924,83 @@ succeeded:
|
||||
clc
|
||||
ret
|
||||
|
||||
%ifdef USE_BOOTSTRAP
|
||||
;
|
||||
; INT 18h entry point.
|
||||
;
|
||||
int18h_entry:
|
||||
xor ax, ax
|
||||
mov ds, ax
|
||||
mov es, ax
|
||||
.clear_memory:
|
||||
mov cx, 256
|
||||
mov di, 0x7c00
|
||||
rep stosw
|
||||
.read_boot_sector:
|
||||
mov dx, REG_SCRATCH_0
|
||||
in al, dx
|
||||
mov dl, al
|
||||
xor dh, dh
|
||||
mov ax, 0x201 ; read 1 sector
|
||||
mov cx, 1 ; sector 1
|
||||
mov bx, 0x7c00
|
||||
int 0x13
|
||||
.test_signature:
|
||||
cmp word [0x7c00+510], 0xaa55
|
||||
jne .no_boot
|
||||
%if %isdef(USE_BOOTSTRAP) && %isdef(FORCE_OWN_BOOTSTRAP)
|
||||
.update_bda:
|
||||
;
|
||||
; Increment the number of fixed disks in the BIOS Data Area, since we did not do it earlier.
|
||||
;
|
||||
mov ax, num_drives_msg
|
||||
call print_string
|
||||
mov ax, 0x40 ; BIOS data area
|
||||
mov es, ax
|
||||
inc byte es:[0x75] ; HDNUM
|
||||
mov al, es:[0x75]
|
||||
call print_hex
|
||||
mov ax, newline
|
||||
call print_string
|
||||
%endif
|
||||
.jump_to_boot:
|
||||
mov ax, boot_msg
|
||||
call print_string
|
||||
xor ax, ax
|
||||
mov es, ax
|
||||
jmp 0:0x7c00
|
||||
.no_boot:
|
||||
mov ax, no_boot_msg
|
||||
call print_string
|
||||
sti
|
||||
.loop:
|
||||
hlt
|
||||
jmp .loop
|
||||
%endif
|
||||
|
||||
;
|
||||
; Disk utilities
|
||||
;
|
||||
|
||||
%ifdef TAKE_OVER_FIXED_DISK_0
|
||||
swap_fixed_disk_parameters_tables:
|
||||
push es
|
||||
push ax
|
||||
push bx
|
||||
xor ax, ax ; INT vector segment
|
||||
mov es, ax
|
||||
mov ax, es:[0x41*4+2]
|
||||
xchg es:[0x46*4+2], ax
|
||||
mov es:[0x41*4+2], ax
|
||||
mov ax, es:[0x41*4+0]
|
||||
xchg es:[0x46*4+0], ax
|
||||
mov es:[0x41*4+0], ax
|
||||
pop bx
|
||||
pop ax
|
||||
pop es
|
||||
ret
|
||||
%endif
|
||||
|
||||
;
|
||||
; Compute LBA address based on CHS address
|
||||
; in: CH = cylinder number (low 8 bits)
|
||||
@@ -931,28 +1092,30 @@ init_sd:
|
||||
push cx
|
||||
push dx
|
||||
push si
|
||||
%ifndef AS_COM_PROGRAM
|
||||
mov ax, ROM_SEGMENT
|
||||
mov ax, cs
|
||||
mov ds, ax
|
||||
%endif
|
||||
mov dx, 0x282 ; chip select port
|
||||
mov dx, REG_CS
|
||||
mov al, 1 ; deassert chip select
|
||||
.power_up_delay:
|
||||
out dx, al
|
||||
xor cx, cx
|
||||
mov dx, 1000 ; microseconds
|
||||
mov cx, 0x0001
|
||||
mov dx, 0x86a0 ; 0x186a0 = 100 ms
|
||||
mov ah, 0x86 ; wait
|
||||
int 0x15
|
||||
mov dx, 0x280 ; data port
|
||||
.dummy_cycles:
|
||||
mov dx, REG_DATA
|
||||
mov al, 0xff
|
||||
mov cx, 80 ; send 80 clock cycles
|
||||
mov cx, 10 ; send 80 clock cycles
|
||||
.synchronize:
|
||||
out dx, al
|
||||
loop .synchronize
|
||||
.assert_cs:
|
||||
mov dx, 0x282 ; chip select port
|
||||
mov dx, REG_CS
|
||||
mov al, 0 ; assert chip select
|
||||
out dx, al
|
||||
.cmd0:
|
||||
mov bx, 10 ; retries
|
||||
.retry_cmd0:
|
||||
%ifdef DEBUG_IO
|
||||
mov ax, send_cmd0_msg
|
||||
call print_string
|
||||
@@ -961,7 +1124,16 @@ init_sd:
|
||||
mov cx, 1 ; response is 1 byte
|
||||
mov ah, 1 ; expect idle state
|
||||
call send_sd_init_cmd
|
||||
jc .exit
|
||||
jnc .cmd8
|
||||
.delay_retry_cmd0:
|
||||
xor cx, cx
|
||||
mov dx, 20000 ; microseconds
|
||||
mov ah, 0x86 ; wait
|
||||
int 0x15
|
||||
dec bx
|
||||
jnz .retry_cmd0
|
||||
stc
|
||||
jmp .exit
|
||||
.cmd8:
|
||||
%ifdef DEBUG_IO
|
||||
mov ax, send_cmd8_msg
|
||||
@@ -973,7 +1145,9 @@ init_sd:
|
||||
call send_sd_init_cmd
|
||||
jc .exit
|
||||
.acmd41:
|
||||
mov bx, 100 ; retries
|
||||
mov dx, REG_TIMEOUT
|
||||
mov al, 250 ; 2.5 s
|
||||
out dx, al
|
||||
.retry_acmd41:
|
||||
%ifdef DEBUG_IO
|
||||
mov ax, send_acmd41_msg
|
||||
@@ -983,22 +1157,19 @@ init_sd:
|
||||
mov cx, 1 ; response is 1 byte
|
||||
mov ah, 1 ; expect idle state
|
||||
call send_sd_init_cmd
|
||||
; TODO: (older cards) on error, try CMD1
|
||||
; TODO: (older cards): handle v1 vs v2
|
||||
mov si, acmd41
|
||||
mov cx, 1 ; response is 1 byte
|
||||
mov ah, 0 ; expect ready state
|
||||
call send_sd_init_cmd
|
||||
jnc .exit
|
||||
pushf
|
||||
xor cx, cx
|
||||
mov dx, 1000 ; microseconds
|
||||
mov ah, 0x86 ; wait
|
||||
int 0x15
|
||||
popf
|
||||
dec bx
|
||||
jnz .retry_acmd41
|
||||
; TODO: (older cards) send CMD16 to set block size
|
||||
mov dx, REG_TIMEOUT
|
||||
in al, dx
|
||||
test al, al
|
||||
jz .retry_acmd41
|
||||
stc
|
||||
.exit:
|
||||
; TODO: (older cards): retrieve SDHC flag
|
||||
pop si
|
||||
pop dx
|
||||
pop cx
|
||||
@@ -1029,7 +1200,7 @@ init_sd:
|
||||
; FL = <TRASH>
|
||||
;
|
||||
send_sd_init_cmd:
|
||||
mov dx, 0x280 ; data port
|
||||
mov dx, REG_DATA
|
||||
.settle_before:
|
||||
mov al, 0xff
|
||||
out dx, al
|
||||
@@ -1078,21 +1249,25 @@ acmd41 db 0x69, 0x40, 0x00, 0x00, 0x00, 0x01
|
||||
; FL = <TRASH>
|
||||
;
|
||||
send_sd_read_write_cmd:
|
||||
mov dx, 0x280 ; data port
|
||||
mov dx, XTMAX_IO_BASE+0 ; data port
|
||||
push ax
|
||||
.settle_before:
|
||||
mov al, 0xff
|
||||
out dx, al
|
||||
.send_cmd:
|
||||
mov al, cl ; command byte
|
||||
mov ah, bh ; address byte 1
|
||||
out dx, ax
|
||||
pop ax ; address byte 3
|
||||
xchg al, bl ; address byte 2
|
||||
out dx, ax
|
||||
xchg al, bl ; address byte 4
|
||||
mov ah, 0x1 ; crc (dummy)
|
||||
out dx, ax
|
||||
out dx, al
|
||||
mov al, bh ; address byte 1
|
||||
out dx, al
|
||||
mov al, bl ; address byte 2
|
||||
out dx, al
|
||||
pop ax
|
||||
xchg al, ah ; address byte 3
|
||||
out dx, al
|
||||
xchg al, ah ; address byte 4
|
||||
out dx, al
|
||||
mov al, 0x1 ; crc (dummy)
|
||||
out dx, al
|
||||
mov cx, 8 ; retries
|
||||
.receive_r1:
|
||||
in al, dx
|
||||
@@ -1108,21 +1283,6 @@ send_sd_read_write_cmd:
|
||||
; General utilities
|
||||
;
|
||||
|
||||
;
|
||||
; Wait 1 microseconds.
|
||||
; out: AX = <TRASH>
|
||||
; FL = <TRASH>
|
||||
delay_us:
|
||||
push cx
|
||||
push dx
|
||||
xor cx, cx
|
||||
mov dx, 1 ; microseconds
|
||||
mov ah, 0x86 ; wait
|
||||
int 0x15
|
||||
pop dx
|
||||
pop cx
|
||||
ret
|
||||
|
||||
%include "utils.inc"
|
||||
|
||||
%ifdef DEBUG
|
||||
@@ -1147,16 +1307,16 @@ debug_handler:
|
||||
|
||||
welcome_msg db 'BootROM for XTMax v1.0', 0xD, 0xA
|
||||
db 'Copyright (c) 2025 Matthieu Bucchianeri', 0xD, 0xA, 0
|
||||
string_io_msg db 'CPU supports INS/OUTS instructions', 0xD, 0xA, 0
|
||||
old_13h_msg db 'Old INT13h Vector = ', 0
|
||||
new_13h_msg db 'New INT13h Vector = ', 0
|
||||
new_fdpt_msg db 'New Fixed Disk Parameter Table = ', 0
|
||||
rom_base_msg db 'ROM Base Address = ', 0
|
||||
init_ok_msg db 'SD Card initialized successfully', 0xD, 0xA, 0
|
||||
init_error_msg db 'SD Card failed to initialize', 0xD, 0xA, 0
|
||||
disk_id_msg db 'Fixed Disk ID = ', 0
|
||||
num_drives_msg db 'Total Fixed Disk Drives = ', 0
|
||||
unsupported_msg db 'Unsupported INT13h Function ', 0
|
||||
colon db ':', 0
|
||||
space db ' ', 0
|
||||
newline db 0xD, 0xA, 0
|
||||
%ifdef USE_BOOTSTRAP
|
||||
boot_msg db 'Booting from SD Card...', 0xD, 0xA, 0
|
||||
no_boot_msg db 'Not bootable', 0xD, 0xA, 0
|
||||
%endif
|
||||
|
||||
%ifdef DEBUG
|
||||
handler_msg db 'INT13h Function ', 0
|
||||
@@ -1182,3 +1342,8 @@ sd_idle_msg db 'Received idle', 0xD, 0xA, 0
|
||||
times 2047-($-$$) db 0
|
||||
db 0 ; will be used to complete the checksum.
|
||||
%endif
|
||||
|
||||
;
|
||||
; The virtual buffer for I/O follows the ROM immediately.
|
||||
;
|
||||
end_of_rom:
|
||||
|
||||
Reference in New Issue
Block a user