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Remove some of the debug features to make the code more readable.

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This commit is contained in:
Matthieu Bucchianeri
2025-02-08 19:05:02 -08:00
committed by Ted Fried
parent 671b6e8153
commit 1186841266
2 changed files with 84 additions and 208 deletions
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128
XTMax/Drivers/BootROM/bootrom.asm
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@@ -14,40 +14,26 @@ cpu 8086 ; ensure we remain compatible with 8086
%define FIXED_DISK_0 (0)
%define FIXED_DISK_1 (1)
%define FLOPPY_DISK (-0x80)
;
; Whether we will emulate the 1st or 2nd disk.
;
%define DISK_NUMBER FIXED_DISK_0
%define EMULATE_FIXED_DISK (DISK_NUMBER >= FIXED_DISK_0)
;
; Whether we will use our own bootstrap code.
;
;%define USE_BOOTSTRAP
;
; The properties of our emulated disk.
;
%if EMULATE_FIXED_DISK
%define NUM_CYLINDERS (1024)
%define NUM_HEADS (16)
%define SECTORS_PER_TRACK (63)
; the last cylinder is reserved on fixed disks
%define NUM_SECTORS (NUM_HEADS * (NUM_CYLINDERS - 1) * SECTORS_PER_TRACK)
%else
%define NUM_HEADS (2)
%define SECTORS_PER_TRACK (18)
%define NUM_CYLINDERS (80)
%define NUM_SECTORS (NUM_HEADS * NUM_CYLINDERS * SECTORS_PER_TRACK)
%endif
; TODO: (feature) the BIOS only specifies 16 heads, however the INT13h functions could use 256.
%if NUM_HEADS > 16
%error NUM_HEADS must be 4 bits
%endif
%if EMULATE_FIXED_DISK && SECTORS_PER_TRACK > 63
%if SECTORS_PER_TRACK > 63
%error SECTORS_PER_TRACK must be 6 bits
%endif
%if NUM_CYLINDERS > 1024
@@ -162,7 +148,6 @@ entry:
mov ax, newline
call print_string
%if EMULATE_FIXED_DISK
;
; Install our fixed disk parameter table.
; For the 1st disk, it is stored in the interrupt vector table, at vector 41h.
@@ -183,34 +168,12 @@ entry:
mov ax, newline
call print_string
%ifdef USE_BOOTSTRAP
;
; Install our BIOS INT18h hook into the interrupt vector table.
;
.install_18h_vector:
mov ax, new_18h_msg
call print_string
mov ax, ROM_SEGMENT
mov es:[0x18*4+2], ax ; store segment
call print_hex
mov ax, colon
call print_string
mov ax, int18h_entry
mov es:[0x18*4], ax ; store offset
call print_hex
mov ax, newline
call print_string
%else
;
; Increment the number of fixed disks in the BIOS Data Area.
;
mov ax, 0x40 ; BIOS data area
mov es, ax
inc byte es:[0x75] ; HDNUM
%endif
%endif
.skip:
sti
@@ -259,19 +222,6 @@ int13h_entry:
; This is not an operation for the SD Card. Forward to the BIOS INT 13h handler.
;
.forward_to_bios:
%ifdef EXTRA_DEBUG
push ax
mov ax, forward_msg
call print_string
pop ax
push ax
mov al, ah
xor ah, ah
call print_hex
mov ax, newline
call print_string
pop ax
%endif
mov TEMP0, ax ; save ax
mov TEMP1, dx ; save dx
pushf ; setup for iret from INT 13h handler
@@ -306,11 +256,7 @@ int13h_entry:
; This is an operation for the SD Card. Use our own INT 13h logic.
;
.check_function:
%if EMULATE_FIXED_DISK
cmp ah, 0x15 ; is valid function?
%else
cmp ah, 0x16 ; is valid function?
%endif
jle .prepare_call
call func_unsupported
jmp .update_bda
@@ -405,9 +351,6 @@ func_table:
dw func_unsupported ; diagnostics
dw func_10_is_ready ; diagnostics
dw func_15_read_size
%if !EMULATE_FIXED_DISK
dw func_10_is_ready ; detect_change
%endif
func_unsupported:
%ifdef DEBUG
@@ -807,29 +750,9 @@ func_08_read_params:
mov es, ax
mov dl, es:[0x75] ; HDNUM
pop es
%ifndef USE_BOOTSTRAP
inc dl ; we never added ourselves
%endif
%if EMULATE_FIXED_DISK
; the last cylinder is reserved on fixed disks
mov ch, ((NUM_CYLINDERS - 2) & 0xff)
mov cl, (((NUM_CYLINDERS - 2) & 0x300) >> 2) | SECTORS_PER_TRACK
%else
mov ch, ((NUM_CYLINDERS - 1) & 0xff)
mov cl, (((NUM_CYLINDERS - 1) & 0x300) >> 2) | SECTORS_PER_TRACK
; diskette drive parameters table, it is stored in the interrupt vector table, at vector 1Eh.
xor ax, ax ; INT vector segment
mov es, ax
mov ax, es:[0x1e*4] ; offset
mov di, ax
mov ax, es:[0x1e*4+2] ; segment
mov es, ax
mov bx, 0x4 ; 1.44 MB
%endif
xor ax, ax
clc
.exit:
@@ -885,13 +808,9 @@ func_15_read_size:
%ifdef DEBUG
call debug_handler
%endif
%if EMULATE_FIXED_DISK
mov ah, 0x3 ; drive present
call get_max_lba
xchg cx, dx
%else
mov ah, 0x1 ; diskette drive present
%endif
clc
ret
@@ -918,36 +837,6 @@ succeeded:
clc
ret
%ifdef USE_BOOTSTRAP
;
; INT 18h entry point.
;
int18h_entry:
xor ax, ax
mov ds, ax
mov es, ax
mov cx, 256
mov di, 0x7c00
rep stosw
mov ax, 0x201 ; read 1 sector
mov dx, 0x80+DISK_NUMBER
mov cx, 1 ; sector 1
mov bx, 0x7c00
int 0x13
cmp word [0x7c00+510], 0xaa55
jne .no_boot
mov ax, boot_msg
call print_string
jmp 0:0x7c00
.no_boot:
mov ax, no_boot_msg
call print_string
sti
.loop:
hlt
jmp .loop
%endif
;
; Disk utilities
;
@@ -967,12 +856,10 @@ compute_lba:
push dx
push cx
push dx
%if EMULATE_FIXED_DISK
mov al, cl
and al, 0xc0
shl ax, 1
shl ax, 1
%endif
mov al, ch ; cylinder
mov cx, NUM_HEADS
mul cx ; cylinder * hpc
@@ -985,9 +872,7 @@ compute_lba:
pop cx
push cx
xor ch, ch
%if EMULATE_FIXED_DISK
and cl, 0x3f
%endif
dec cx ; sector - 1
add ax, cx ; (cylinder * hpc + head) * spt + (sector - 1)
adc dx, 0 ; carry
@@ -1270,11 +1155,6 @@ new_fdpt_msg db 'New Fixed Disk Parameter Table = ', 0
init_ok_msg db 'SD Card initialized successfully', 0xD, 0xA, 0
init_error_msg db 'SD Card failed to initialize', 0xD, 0xA, 0
unsupported_msg db 'Unsupported INT13h Function ', 0
%ifdef USE_BOOTSTRAP
new_18h_msg db 'New INT18h Vector = ', 0
boot_msg db 'Booting from SD Card...', 0xD, 0xA, 0
no_boot_msg db 'Not bootable', 0xD, 0xA, 0
%endif
colon db ':', 0
space db ' ', 0
newline db 0xD, 0xA, 0
@@ -1294,10 +1174,6 @@ sd_token_msg db 'Received token', 0xD, 0xA, 0
sd_status_msg db 'Received status ', 0
sd_idle_msg db 'Received idle', 0xD, 0xA, 0
%endif
%ifdef EXTRA_DEBUG
forward_msg db 'Forward to BIOS INT13h handler ', 0
%endif
%endif
%ifndef AS_COM_PROGRAM