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Major rework of IO to use MOVSW.

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This commit is contained in:
Matthieu Bucchianeri
2025-02-15 16:44:10 -08:00
parent 730b632510
commit 9535b0f878
6 changed files with 273 additions and 295 deletions
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219
XTMax/Drivers/BootROM/bootrom.asm
View File

@@ -16,22 +16,11 @@ cpu 8086 ; ensure we remain compatible with 8086
;
%define XTMAX_IO_BASE (0x280)
%define FIXED_DISK_0 (0)
%define FIXED_DISK_1 (1)
;
; Whether we will emulate the 1st or 2nd disk.
;
%define DISK_NUMBER FIXED_DISK_0
%if DISK_NUMBER == FIXED_DISK_0
;
; 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
%endif
;
; Whether we will try/force using our own bootstrap code instead of falling back to BASIC.
@@ -97,57 +86,6 @@ entry:
jc .skip
%endif
;
; Detecting 80186-compatible so we can use REP INSW/OUTSW.
; Based on https://cosmodoc.org/topics/processor-detection/
;
.cpuid:
; Push a zero value to the stack, then immediately pop that zero
; value into the FLAGS register. Depending on the CPU, some bits will
; refuse this change and remain on.
xor ax, ax
push ax
popf
; Push the current state of FLAGS to the stack, then immediately pop
; the flag state into AX for further analysis.
pushf
pop ax
; Consider only flag bits 12..15, and see if they all remained on.
and ax, 0xf000
cmp ax, 0xf000
jne .support_string_io ; at least 80286
; Perform "FFh >> 33" then check for a zero or nonzero result.
mov al, 0xff
mov cl, 0x21
shr al, cl
jnz .support_string_io ; at least 80186/80188
; Ensure interrupts are enabled, then save SI's value on the stack.
sti
; Here, ES is pointing to some unspecified place in memory. Below is
; a busy loop that reads 64 KiB of memory from ES:SI, loading each
; byte into AL and doing nothing further with it. After each
; iteration, SI is incremented and CX is decremented. The loop ends
; when CX reaches zero. Or does it?
mov si, 0
mov cx, 0xffff
rep lodsb
; See if the value in CX made it all the way to zero. If it did, the
; CPU is a V30 or V20.
or cx, cx
cli
jz .support_string_io ; at least V20
.not_support_string_io:
xor dl, dl
jmp .store_string_io
.support_string_io:
mov dl, 1
mov ax, string_io_msg
call print_string
.store_string_io:
mov ax, XTMAX_IO_BASE+3 ; scratch register 0
xchg ax, dx
out dx, al ; save capability
%ifndef AS_COM_PROGRAM
;
; Install our BIOS INT13h hook into the interrupt vector table.
@@ -160,31 +98,22 @@ entry:
mov es, ax
mov ax, es:[0x13*4+2]
mov dx, XTMAX_IO_BASE+4 ; scratch register 1-2
mov dx, XTMAX_IO_BASE+3 ; scratch register 0-1
out dx, ax ; save segment
call print_hex
mov ax, colon
call print_string
mov ax, es:[0x13*4]
mov dx, XTMAX_IO_BASE+6 ; scratch register 3-4
mov dx, XTMAX_IO_BASE+5 ; scratch register 2-3
out dx, ax ; save offset
call print_hex
mov ax, newline
call print_string
mov ax, new_13h_msg
call print_string
mov ax, ROM_SEGMENT
mov es:[0x13*4+2], ax ; store segment
call print_hex
mov ax, colon
call print_string
mov ax, int13h_entry
mov es:[0x13*4], ax ; store offset
call print_hex
mov ax, newline
call print_string
;
; Move fixed disk 0 to fixed disk 1.
@@ -199,19 +128,29 @@ entry:
; For the 2nd disk, it is stored in the interrupt vector table, at vector 46h.
;
.install_fixed_disk_parameters_table:
mov ax, new_fdpt_msg
mov ax, disk_id_msg
call print_string
mov ax, ROM_SEGMENT
mov es:[(0x41+DISK_NUMBER*5)*4+2], ax ; store segment
call print_hex
mov ax, colon
call print_string
mov ax, fixed_disk_parameters_table
mov es:[(0x41+DISK_NUMBER*5)*4], ax ; store offset
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
cmp al, 0x80
jne .second_disk
mov ax, ROM_SEGMENT
mov es:[0x41*4+2], ax ; store segment
mov ax, fixed_disk_parameters_table
mov es:[0x41*4+0], ax ; store offset
jmp .end_fdpt
.second_disk:
mov ax, ROM_SEGMENT
mov es:[0x46*4+2], ax ; store segment
mov ax, fixed_disk_parameters_table
mov es:[0x46*4+0], ax ; store offset
.end_fdpt:
%ifdef USE_BOOTSTRAP
.update_bda:
@@ -219,19 +158,10 @@ entry:
; 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
%endif
%if !(%isdef(USE_BOOTSTRAP) && %isdef(FORCE_OWN_BOOTSTRAP))
@@ -292,7 +222,13 @@ int13h_entry:
%endif
push TEMP0
push TEMP1
cmp dl, 0x80+DISK_NUMBER ; is this our drive?
push ax
push dx
mov dx, XTMAX_IO_BASE+2 ; fixed disk id
in al, dx
pop dx
cmp dl, al ; is this our drive?
pop ax
je .check_function
;
@@ -317,14 +253,14 @@ int13h_entry:
; Simulate INT 13h with the original vector.
;
pushf ; setup for iret below
mov dx, XTMAX_IO_BASE+4 ; scratch register 1-2
mov dx, XTMAX_IO_BASE+3 ; scratch register 0-1
%ifndef AS_COM_PROGRAM
in ax, dx
%else
mov ax, cs
%endif
push ax ; setup for iret below
mov dx, XTMAX_IO_BASE+6 ; scratch register 3-4
mov dx, XTMAX_IO_BASE+5 ; scratch register 2-3
%ifndef AS_COM_PROGRAM
in ax, dx
%else
@@ -546,6 +482,7 @@ func_02_read_sector:
jc error_sector_not_found
; TODO: (robustness) check buffer boundaries
.setup:
push ds
push bx
push cx
push dx
@@ -553,7 +490,11 @@ func_02_read_sector:
push ax
mov cx, ax ; number of sectors to read
xor ch, ch
mov di, bx ; setup use of stosw
%ifndef AS_COM_PROGRAM
mov ax, ROM_SEGMENT
mov ds, ax
%endif
mov di, bx ; setup use of movsw
.assert_cs:
mov dx, XTMAX_IO_BASE+2 ; chip select port
mov al, 0 ; assert chip select
@@ -574,7 +515,7 @@ func_02_read_sector:
mov ax, wait_msg
call print_string
%endif
mov dx, XTMAX_IO_BASE+15; timeout port
mov dx, XTMAX_IO_BASE+7 ; timeout port
mov al, 10 ; 100 ms
out dx, al
.receive_token:
@@ -582,7 +523,7 @@ func_02_read_sector:
in al, dx
cmp al, 0xfe
je .got_token
mov dx, XTMAX_IO_BASE+15; timeout port
mov dx, XTMAX_IO_BASE+7 ; timeout port
in al, dx
test al, al
jnz .error
@@ -593,22 +534,12 @@ func_02_read_sector:
call print_string
%endif
mov cx, 256 ; block size (in words)
push dx
mov dx, XTMAX_IO_BASE+3 ; scratch register 0
in al, dx
pop dx
test al, al ; supports insw?
push si
mov si, end_of_rom ; virtual buffer
cld
jz .receive_block
.receive_block_fast:
cpu 186
rep insw
cpu 8086
jmp .receive_crc
.receive_block:
in ax, dx
stosw
loop .receive_block
rep movsw
pop si
.receive_crc:
in ax, dx ; discard CRC
add TEMP_LO, 1 ; next block
@@ -626,6 +557,7 @@ cpu 8086
pop dx
pop cx
pop bx
pop ds
jmp succeeded
.error:
.deassert_cs2:
@@ -640,6 +572,7 @@ cpu 8086
pop dx
pop cx
pop bx
pop ds
jmp error_drive_not_ready
;
@@ -686,7 +619,11 @@ 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
%ifndef AS_COM_PROGRAM
mov ax, ROM_SEGMENT
mov es, ax
%endif
.assert_cs:
mov dx, XTMAX_IO_BASE+2 ; chip select port
mov al, 0 ; assert chip select
@@ -707,30 +644,19 @@ func_03_write_sector:
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, XTMAX_IO_BASE+3 ; 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 dx, XTMAX_IO_BASE+15; timeout port
mov dx, XTMAX_IO_BASE+7 ; timeout port
mov al, 25 ; 250 ms
out dx, al
.receive_status:
@@ -738,7 +664,7 @@ cpu 8086
in al, dx
cmp al, 0xff
jne .got_status
mov dx, XTMAX_IO_BASE+15; timeout port
mov dx, XTMAX_IO_BASE+7 ; timeout port
in al, dx
test al, al
jnz .error
@@ -763,7 +689,7 @@ cpu 8086
mov ax, wait_msg
call print_string
%endif
mov dx, XTMAX_IO_BASE+15; timeout port
mov dx, XTMAX_IO_BASE+7 ; timeout port
mov al, 25 ; 250 ms
out dx, al
.receive_finish:
@@ -771,7 +697,7 @@ cpu 8086
in al, dx
test al, al
jnz .got_finish
mov dx, XTMAX_IO_BASE+15; timeout port
mov dx, XTMAX_IO_BASE+7 ; timeout port
in al, dx
test al, al
jnz .error
@@ -796,6 +722,8 @@ cpu 8086
mov al, 1 ; deassert chip select
out dx, al
.return1:
mov ax, ds
mov es, ax ; restore es
pop ax
pop di
pop dx
@@ -810,6 +738,8 @@ cpu 8086
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
@@ -971,12 +901,15 @@ int18h_entry:
xor ax, ax
mov ds, ax
mov es, ax
.read_boot_sector:
.clear_memory:
mov cx, 256
mov di, 0x7c00
rep stosw
.read_boot_sector:
mov dx, XTMAX_IO_BASE+2 ; fixed disk id
in al, dx
mov dl, al
mov ax, 0x201 ; read 1 sector
mov dx, 0x80+DISK_NUMBER
mov cx, 1 ; sector 1
mov bx, 0x7c00
int 0x13
@@ -1182,7 +1115,7 @@ init_sd:
call send_sd_init_cmd
jc .exit
.acmd41:
mov dx, XTMAX_IO_BASE+15; timeout port
mov dx, XTMAX_IO_BASE+7 ; timeout port
mov al, 250 ; 2.5 s
out dx, al
.retry_acmd41:
@@ -1200,7 +1133,7 @@ init_sd:
mov ah, 0 ; expect ready state
call send_sd_init_cmd
jnc .exit
mov dx, XTMAX_IO_BASE+15; timeout port
mov dx, XTMAX_IO_BASE+7 ; timeout port
in al, dx
test al, al
jz .retry_acmd41
@@ -1340,16 +1273,13 @@ 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
old_13h_msg db 'Old INT13h Vector = ', 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
%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
@@ -1381,3 +1311,8 @@ 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:

2
XTMax/Drivers/BootROM/build.cmd
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@@ -1,2 +1,2 @@
..\Driver_Build_Tools\NASM\nasm.exe -f bin -o bootrom.com -DAS_COM_PROGRAM .\bootrom.asm
..\Driver_Build_Tools\NASM\nasm.exe -f bin -o bootrom .\bootrom.asm & python checksum.py
..\Driver_Build_Tools\NASM\nasm.exe -f bin -o bootrom .\bootrom.asm & python checksum.py & python generate_header.py

17
XTMax/Drivers/BootROM/checksum.py
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@@ -1,23 +1,6 @@
# https://stackoverflow.com/questions/53808694/how-do-i-format-a-python-list-as-an-initialized-c-array
def to_c_array(values, ctype="float", name="table", formatter=str, colcount=8):
# apply formatting to each element
values = [formatter(v) for v in values]
# split into rows with up to `colcount` elements per row
rows = [values[i:i+colcount] for i in range(0, len(values), colcount)]
# separate elements with commas, separate rows with newlines
body = ',\n '.join([', '.join(r) for r in rows])
# assemble components into the complete string
return '{} {}[] = {{\n {}}};'.format(ctype, name, body)
with open("bootrom", "rb") as f:
b = bytearray(f.read())
# compute the checksum and store a byte to
b[-1] = 256 - sum(b[0:-1]) & 0xff
with open("bootrom", "wb") as f:
f.write(b)
with open("../../Code/XTMax/bootrom.h", "w") as f:
f.write("#define BOOTROM_ADDR 0xCE000\n")
f.write(to_c_array(b, ctype="unsigned char", name="BOOTROM", colcount=16))

27
XTMax/Drivers/BootROM/generate_header.py Normal file
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@@ -0,0 +1,27 @@
segment = None
with open("bootrom.asm", "r") as f:
for line in f:
if line.startswith('%define ROM_SEGMENT'):
segment = int(line[19:].strip('() \n'), 16)
break
with open("bootrom", "rb") as f:
bitstream = bytearray(f.read())
# https://stackoverflow.com/questions/53808694/how-do-i-format-a-python-list-as-an-initialized-c-array
def to_c_array(values, ctype="float", name="table", formatter=str, colcount=8):
# apply formatting to each element
values = [formatter(v) for v in values]
# split into rows with up to `colcount` elements per row
rows = [values[i:i+colcount] for i in range(0, len(values), colcount)]
# separate elements with commas, separate rows with newlines
body = ',\n '.join([', '.join(r) for r in rows])
# assemble components into the complete string
return '{} {}[] = {{\n {}}};'.format(ctype, name, body)
with open("../../Code/XTMax/bootrom.h", "w") as f:
f.write("#define BOOTROM_ADDR {}\n".format(hex(segment << 4)))
f.write(to_c_array(bitstream, ctype="unsigned char", name="BOOTROM", colcount=16))