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More code reorg and auto-detecting second drive.

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This commit is contained in:
Matthieu Bucchianeri
2025-02-15 18:15:53 -08:00
parent 9535b0f878
commit 923bbd548e
3 changed files with 260 additions and 223 deletions
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221
XTMax/Drivers/BootROM/bootrom.asm
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@@ -15,12 +15,15 @@ cpu 8086 ; ensure we remain compatible with 8086
; The base I/O port for the XTMAX SD Card.
;
%define XTMAX_IO_BASE (0x280)
;
; Whether we are going to rename the BIOS's 1st disk to be the second disk.
; This is useful to allow booting from the second disk.
;
;%define TAKE_OVER_FIXED_DISK_0
%define REG_DATA (XTMAX_IO_BASE+0)
%define REG_CS (XTMAX_IO_BASE+1) ; write-only
%define REG_CONFIG (XTMAX_IO_BASE+1) ; read-only
%define REG_SCRATCH_0 (XTMAX_IO_BASE+2) ; fixed disk id
%define REG_SCRATCH_1 (XTMAX_IO_BASE+3) ; BIOS INT13h segment
%define REG_SCRATCH_2 (XTMAX_IO_BASE+4) ; BIOS INT13h segment
%define REG_SCRATCH_3 (XTMAX_IO_BASE+5) ; BIOS INT13h offset
%define REG_SCRATCH_4 (XTMAX_IO_BASE+6) ; BIOS INT13h offset
%define REG_TIMEOUT (XTMAX_IO_BASE+7)
;
; Whether we will try/force using our own bootstrap code instead of falling back to BASIC.
@@ -28,6 +31,12 @@ cpu 8086 ; ensure we remain compatible with 8086
%define USE_BOOTSTRAP
;%define FORCE_OWN_BOOTSTRAP
;
; Whether we are going to rename the BIOS's 1st disk to be the second disk.
; This is useful to allow booting from the second disk.
;
;%define TAKE_OVER_FIXED_DISK_0
;
; The properties of our emulated disk.
;
@@ -38,13 +47,16 @@ cpu 8086 ; ensure we remain compatible with 8086
%define NUM_SECTORS (NUM_HEADS * (NUM_CYLINDERS - 1) * SECTORS_PER_TRACK)
%if NUM_HEADS > 255
%error NUM_HEADS is too large
%error NUM_HEADS_ is too large
%endif
%if NUM_HEADS > 16
%warning NUM_HEADS_ above 16 can cause compatibility issues
%endif
%if SECTORS_PER_TRACK > 63
%error SECTORS_PER_TRACK is too large
%error SECTORS_PER_TRACK_ is too large
%endif
%if NUM_CYLINDERS > 1024
%error NUM_CYLINDERS is too large
%error NUM_CYLINDERS_ is too large
%endif
%ifndef AS_COM_PROGRAM
@@ -93,23 +105,20 @@ entry:
.install_13h_vector:
mov ax, old_13h_msg
call print_string
xor ax, ax ; INT vector segment
mov es, ax
mov ax, es:[0x13*4+2]
mov dx, XTMAX_IO_BASE+3 ; scratch register 0-1
mov dx, REG_SCRATCH_1
out dx, ax ; save segment
call print_hex
mov ax, colon
call print_string
mov ax, es:[0x13*4]
mov dx, XTMAX_IO_BASE+5 ; scratch register 2-3
mov dx, REG_SCRATCH_3
out dx, ax ; save offset
call print_hex
mov ax, newline
call print_string
mov ax, ROM_SEGMENT
mov es:[0x13*4+2], ax ; store segment
mov ax, int13h_entry
@@ -122,22 +131,50 @@ entry:
call swap_fixed_disk_parameters_tables
%endif
;
; Determine our fixed disk ID.
;
.identify_fixed_disk:
mov ax, disk_id_msg
call print_string
mov ax, 0x40 ; BIOS data area
mov es, ax
%ifndef TAKE_OVER_FIXED_DISK_0
mov al, es:[0x75] ; HDNUM
add al, 0x80
%else
mov al, 0x80
%endif
mov dx, REG_SCRATCH_0 ; save fixed disk id
out dx, al
push ax
call print_hex
mov ax, newline
call print_string
%if !(%isdef(USE_BOOTSTRAP) && %isdef(FORCE_OWN_BOOTSTRAP))
.update_bda:
;
; Increment the number of fixed disks in the BIOS Data Area.
;
mov ax, num_drives_msg
call print_string
inc byte es:[0x75] ; HDNUM
mov al, es:[0x75]
xor ah, ah
call print_hex
mov ax, newline
call print_string
%endif
pop ax
;
; Install our fixed disk parameter table.
; For the 1st disk, it is stored in the interrupt vector table, at vector 41h.
; For the 2nd disk, it is stored in the interrupt vector table, at vector 46h.
;
.install_fixed_disk_parameters_table:
mov ax, disk_id_msg
call print_string
mov dx, XTMAX_IO_BASE+2 ; fixed disk id
in al, dx
xor ah, ah
push ax
call print_hex
mov ax, newline
call print_string
pop ax
xor cx, cx ; INT vector segment
mov es, cx
cmp al, 0x80
jne .second_disk
mov ax, ROM_SEGMENT
@@ -153,7 +190,6 @@ entry:
.end_fdpt:
%ifdef USE_BOOTSTRAP
.update_bda:
;
; Install our BIOS INT18h hook into the interrupt vector table.
;
@@ -164,21 +200,6 @@ entry:
mov es:[0x18*4], ax ; store offset
%endif
%if !(%isdef(USE_BOOTSTRAP) && %isdef(FORCE_OWN_BOOTSTRAP))
;
; Increment the number of fixed disks in the BIOS Data Area.
;
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
.skip:
sti
pop si
@@ -216,15 +237,21 @@ entry:
; INT 13h entry point.
;
int13h_entry:
sti
%ifdef EXTRA_DEBUG
push TEMP0
mov TEMP0, sp
mov TEMP0, [TEMP0+6] ; grab the flags for iret
push TEMP0
popf
pop TEMP0
call dump_regs
%endif
sti
push TEMP0
push TEMP1
push ax
push dx
mov dx, XTMAX_IO_BASE+2 ; fixed disk id
mov dx, REG_SCRATCH_0
in al, dx
pop dx
cmp dl, al ; is this our drive?
@@ -236,9 +263,9 @@ int13h_entry:
;
.forward_to_bios:
%ifdef TAKE_OVER_FIXED_DISK_0
cmp dl, 0x80+FIXED_DISK_1 ; is this the other fixed drive?
cmp dl, 0x81 ; is this the other fixed drive?
jne .no_fixed_disk_take_over
mov dl, 0x80+FIXED_DISK_0
mov dl, 0x80
call swap_fixed_disk_parameters_tables
.no_fixed_disk_take_over:
%endif
@@ -252,32 +279,33 @@ int13h_entry:
;
; Simulate INT 13h with the original vector.
;
pushf ; setup for iret below
mov dx, XTMAX_IO_BASE+3 ; scratch register 0-1
mov dx, REG_SCRATCH_1
%ifndef AS_COM_PROGRAM
in ax, dx
%else
mov ax, cs
%endif
push ax ; setup for iret below
mov dx, XTMAX_IO_BASE+5 ; scratch register 2-3
push ax ; setup for retf below
mov dx, REG_SCRATCH_3
%ifndef AS_COM_PROGRAM
in ax, dx
%else
mov ax, fake_int13h_entry
%endif
push ax ; setup for iret below
push ax ; setup for retf below
mov ax, TEMP0 ; restore ax
mov dx, TEMP1 ; restore dx
iret ; call the INT 13h handler
cli ; INT inhibits interrupts
retf ; call the INT 13h handler
.return_from_int13h:
sti ; just in case
pushf
push ax
mov ax, TEMP1 ; original dx
cmp al, 0x80 ; is fixed fixed?
jb .skip_update_hdnum
%ifdef TAKE_OVER_FIXED_DISK_0
mov dl, 0x80+FIXED_DISK_1
mov dl, 0x81
call swap_fixed_disk_parameters_tables
%endif
mov ax, TEMP0 ; original ax
@@ -297,7 +325,7 @@ int13h_entry:
; This is an operation for the SD Card. Use our own INT 13h logic.
;
.check_function:
cmp ah, 0x15 ; is valid function?
cmp ah, 0x19 ; is valid function?
jle .prepare_call
call func_unsupported
jmp .update_bda
@@ -392,6 +420,10 @@ func_table:
dw func_unsupported ; diagnostics
dw func_10_is_ready ; diagnostics
dw func_15_read_size
dw func_unsupported ; detect_change
dw func_unsupported ; set_media_type
dw func_unsupported ; set_media_type
dw func_10_is_ready ; park_heads
func_unsupported:
%ifdef DEBUG
@@ -496,7 +528,7 @@ func_02_read_sector:
%endif
mov di, bx ; setup use of movsw
.assert_cs:
mov dx, XTMAX_IO_BASE+2 ; chip select port
mov dx, REG_CS
mov al, 0 ; assert chip select
out dx, al
.cmd17:
@@ -515,15 +547,15 @@ func_02_read_sector:
mov ax, wait_msg
call print_string
%endif
mov dx, XTMAX_IO_BASE+7 ; timeout port
mov dx, REG_TIMEOUT
mov al, 10 ; 100 ms
out dx, al
.receive_token:
mov dx, XTMAX_IO_BASE+0 ; data port
mov dx, REG_DATA
in al, dx
cmp al, 0xfe
je .got_token
mov dx, XTMAX_IO_BASE+7 ; timeout port
mov dx, REG_TIMEOUT
in al, dx
test al, al
jnz .error
@@ -539,16 +571,16 @@ func_02_read_sector:
cld
.receive_block:
rep movsw
pop si
.receive_crc:
in ax, dx ; discard CRC
lodsw ; discard CRC
pop si
add TEMP_LO, 1 ; next block
adc TEMP_HI, 0 ; carry
pop cx ; number of sectors left to read
loop .cmd17
.success:
.deassert_cs1:
mov dx, XTMAX_IO_BASE+2 ; chip select port
mov dx, REG_CS
mov al, 1 ; deassert chip select
out dx, al
.return1:
@@ -561,7 +593,7 @@ func_02_read_sector:
jmp succeeded
.error:
.deassert_cs2:
mov dx, XTMAX_IO_BASE+2 ; chip select port
mov dx, REG_CS
mov al, 1 ; deassert chip select
out dx, al
.return2:
@@ -625,7 +657,7 @@ func_03_write_sector:
mov es, ax
%endif
.assert_cs:
mov dx, XTMAX_IO_BASE+2 ; chip select port
mov dx, REG_CS
mov al, 0 ; assert chip select
out dx, al
.cmd24:
@@ -640,7 +672,7 @@ func_03_write_sector:
mov cl, 0x58 ; CMD24
call send_sd_read_write_cmd
jc .error
mov dx, XTMAX_IO_BASE+0 ; data port
mov dx, REG_DATA
mov al, 0xfe ; send token
out dx, al
mov cx, 256 ; block size (in words)
@@ -656,15 +688,15 @@ func_03_write_sector:
mov ax, wait_msg
call print_string
%endif
mov dx, XTMAX_IO_BASE+7 ; timeout port
mov dx, REG_TIMEOUT
mov al, 25 ; 250 ms
out dx, al
.receive_status:
mov dx, XTMAX_IO_BASE+0 ; data port
mov dx, REG_DATA
in al, dx
cmp al, 0xff
jne .got_status
mov dx, XTMAX_IO_BASE+7 ; timeout port
mov dx, REG_TIMEOUT
in al, dx
test al, al
jnz .error
@@ -689,15 +721,15 @@ func_03_write_sector:
mov ax, wait_msg
call print_string
%endif
mov dx, XTMAX_IO_BASE+7 ; timeout port
mov dx, REG_TIMEOUT
mov al, 25 ; 250 ms
out dx, al
.receive_finish:
mov dx, XTMAX_IO_BASE+0 ; data port
mov dx, REG_DATA
in al, dx
test al, al
jnz .got_finish
mov dx, XTMAX_IO_BASE+7 ; timeout port
mov dx, REG_TIMEOUT
in al, dx
test al, al
jnz .error
@@ -718,7 +750,7 @@ func_03_write_sector:
%endif
.success:
.deassert_cs1:
mov dx, XTMAX_IO_BASE+2 ; chip select port
mov dx, REG_CS
mov al, 1 ; deassert chip select
out dx, al
.return1:
@@ -733,7 +765,7 @@ func_03_write_sector:
jmp succeeded
.error:
.deassert_cs2:
mov dx, XTMAX_IO_BASE+2 ; chip select port
mov dx, REG_CS
mov al, 1 ; deassert chip select
out dx, al
.return2:
@@ -906,9 +938,10 @@ int18h_entry:
mov di, 0x7c00
rep stosw
.read_boot_sector:
mov dx, XTMAX_IO_BASE+2 ; fixed disk id
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
@@ -955,14 +988,14 @@ swap_fixed_disk_parameters_tables:
push es
push ax
push bx
xor ax, ax
xor ax, ax ; INT vector segment
mov es, ax
mov ax, es:[(0x41+FIXED_DISK_0*5)*4+2]
xchg es:[(0x41+FIXED_DISK_1*5)*4+2], ax
mov es:[(0x41+FIXED_DISK_0*5)*4+2], ax
mov ax, es:[(0x41+FIXED_DISK_0*5)*4]
xchg es:[(0x41+FIXED_DISK_1*5)*4], ax
mov es:[(0x41+FIXED_DISK_0*5)*4], 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
@@ -1064,7 +1097,7 @@ init_sd:
mov ax, ROM_SEGMENT
mov ds, ax
%endif
mov dx, XTMAX_IO_BASE+2 ; chip select port
mov dx, REG_CS
mov al, 1 ; deassert chip select
.power_up_delay:
out dx, al
@@ -1073,14 +1106,14 @@ init_sd:
mov ah, 0x86 ; wait
int 0x15
.dummy_cycles:
mov dx, XTMAX_IO_BASE+0 ; data port
mov dx, REG_DATA
mov al, 0xff
mov cx, 10 ; send 80 clock cycles
.synchronize:
out dx, al
loop .synchronize
.assert_cs:
mov dx, XTMAX_IO_BASE+2 ; chip select port
mov dx, REG_CS
mov al, 0 ; assert chip select
out dx, al
.cmd0:
@@ -1115,7 +1148,7 @@ init_sd:
call send_sd_init_cmd
jc .exit
.acmd41:
mov dx, XTMAX_IO_BASE+7 ; timeout port
mov dx, REG_TIMEOUT
mov al, 250 ; 2.5 s
out dx, al
.retry_acmd41:
@@ -1133,7 +1166,7 @@ init_sd:
mov ah, 0 ; expect ready state
call send_sd_init_cmd
jnc .exit
mov dx, XTMAX_IO_BASE+7 ; timeout port
mov dx, REG_TIMEOUT
in al, dx
test al, al
jz .retry_acmd41
@@ -1170,7 +1203,7 @@ init_sd:
; FL = <TRASH>
;
send_sd_init_cmd:
mov dx, XTMAX_IO_BASE+0 ; data port
mov dx, REG_DATA
.settle_before:
mov al, 0xff
out dx, al
@@ -1226,14 +1259,18 @@ send_sd_read_write_cmd:
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