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Deja Vu #09
13 ноября 1999 |
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Coding - Error Handling TR-DOS when working through # 3D13.
(C) Rezonance group
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Handling Errors TR-DOS when working
through # 3D13.
The key point is to change
system variables TR-DOS at
23749, which is usually located team
RET, is used to refer to the BASIC ROM routines 48. After
intercepting the call determines which subprogram required a
TR-DOS, and a decision about whether to go in BASIC or use an
alternate routine, written by us.
On error reading sector and the protection of
records are accessed in BASIC at the following addresses: #
0D6B - clearing the screen and the opening flux 0; # 0010 -
Print symbol; # 028E, # 031E, # 0333 - all this poll the
keyboard; # 1F54 - poll BREAK; # 1B7B - RST8 (error handler).
It is these routines we have to substitute your own. In
addition to the above, TR-DOS uses a few routines: # 1F1A, #
1F05, # 0030, # 19E5, and etc. to adjust the memory, but it is
better do not touch it, let them work as work.
All remaining errors are returned to the system variable and
processed 23,823 special procedure. We now turn to
the program itself.
An example of a procedure call download the file.
In case 'A' - a way to download.
ORG # 8000,0
DI
LD A, # FF
LD HL, NAME
LD DE, 0
CALL Load_file
In the case of a fatal error control is transferred here. "
ABORT NOP
NOP
NOP
RET
File name and extension.
NAME DEFM "screen2"
DEFM "C"
Variables: the type of load, the address name
file and the load address, file length, address
on the screen.
DOStyp DEFB 0
DOSnam DEFW 0
DOSadr DEFW 0
DOSlen DEFW 0
DOSscr DEFW 0
;------------------------------;| DOWNLOADS |
;------------------------------; IN:
; A - TYPE OF LOAD
; 0 - address and the length of the directory
, 1,2 - address of 'DE', the length of
; Directory
3 - the address of the 'DE', the length of the 'BC'
; HL - FILE NAME ADDRESS
; DE - Load address
; BC - LENGTH OF FILE
Load_file
DI
Save the contents of the registers in memory.
LD (DOStyp), A
LD (DOSnam), HL
LD (DOSadr), DE
LD (DOSlen), BC
Copy the file name in the domain of variables
TR-DOS.
CALL DOS_move_name
These variables are required to install for
normal operation.
LD A, 0
LD (23801), A
LD (23824), A
Preparation of the remaining variables to work.
CALL DOS_instal
In the absence of a file or similar
error message displayed on the screen and
Request Retry, Abort. This cycle is necessary
to repeat the operation in case the answer
Retry.
Lfile01
LD A, (DOStyp)
LD HL, (DOSadr)
LD DE, (DOSlen)
LD BC, 14
CALL # 3D13
CALL DOS_disk_error
JR NZ, Lfile01
Restore the original values of variables
and return.
JP DOS_uninstal
;------------------------------;| SHIPPING FILE |
;------------------------------; IN:
; HL - FILE NAME ADDRESS
; DE - ADDRESS FILE
; BC - LENGTH OF FILE
Here, everything is similar to the procedure for downloading
file.
Save_file
DI
LD (DOSnam), HL
LD (DOSadr), DE
LD (DOSlen), BC
CALL DOS_move_name
LD A, 0
LD (23801), A
LD (23824), A
CALL DOS_instal
Sfile01
LD HL, (DOSadr)
LD DE, (DOSlen)
LD BC, 11
CALL # 3D13
CALL DOS_disk_error
JR NZ, Sfile01
JP DOS_uninstal
;------------------------------
Set the number of characters for which
looking for a file, change the variable ERR_SP,
to easily go back and do not
forget about the team JP.
DOS_instal
LD A, 9
LD (23814), A
LD (23613), SP
LD A, # C3
LD HL, DOS_error_intercept
LD (23746), A
LD (23747), HL
RET
;------------------------------
Once the procedure is fulfilled, will return to the place of
RET. Here can also add command to restore ERR_SP.
DOS_uninstal
LD A, # C9
LD HL, # FFFF
LD (23746), A
LD (23747), HL
RET
;------------------------------
Transferring a file name in the domain of variables
TR-DOS.
DOS_move_name
LD DE, 23773
LD BC, 9
LDIR
RET
;------------------------------; PROCESSING ERROR 'RZ-DOSv1' |
;------------------------------ Enjoying the content 23823: if
there is 0, then file is loaded (shipped) without any problems,
or discover that it is a mistake.
DOS_disk_error
LD A, (23823)
OR A
RET Z
Open the on-screen window.
CALL DOS_window_open
In the 'HL' address error messages.
LD HL, DOS_mezage
Do not pay attention, not just a string
fit on the screen. In the 'BC' length of all messages.
LD BC, DOS_mezage_error-DOS_mezage
Finding us a message by its code in
case 'A'.
DOS_Derror1
CPI
JR Z, DOS_Derror2
JP PE, DOS_Derror1
If the message is found, then the 'HL' address, if not, then
the 'HL' address message "* Indiscernible error *", ie
Unrecognized error.
DOS_Derror2
Print a message in the window
CALL DOS_write_line
Print Retry, Abort? (If, for example,
disc does not have the desired file, then you politely
report it and ask, search
again or be enough? And you at this time
insolent view insert another disk and push "R"!).
LD HL, DOS_mezage_ask
CALL DOS_write_line
Reset the error so that when you answer "R" and
successful completion of the work mysteriously not
an error message.
LD A, 0
LD (23823), A
Poll buttons "R" and "A".
DOS_Derror3
CALL DOS_RAI_ask
CP "A"
JR Z, DOS_abort
CP "R"
JR Z, DOS_retry
JR DOS_Derror3
Close the window, dropping the Z flag and repeat
almost all from the beginning.
DOS_retry
CALL DOS_window_close
OR # FF
RET
Close the window by turning off all that is needed and
go to the caller.
DOS_abort
CALL DOS_window_close
CALL DOS_uninstal
JP ABORT
Error message. Format: error code
newline (why come? so does
DOS), the message 0 - end of message marker.
DOS_mezage
DEFB 1,13
DEFM "No file"
DEFB 0,2,13
DEFM "File exists"
DEFB 0,3,13
DEFM "No space"
DEFB 0,4,13
DEFM "Directory full"
DEFB 0,5,13
DEFM "Rec O / F"
DEFM 0,6,13
DEFM "No disc"
DEFB 0,12,13
DEFM "Break into program"
DEFB 0,20,13
DEFM "Break-cont repeats"
DEFB 0
DOS_mezage_error
; NERASPOZNANAYA RZ-DOSom ERROR!
DEFB 13
DEFM "* Indiscernible error *"
DEFB 0
DOS_mezage_ask
DEFB 13
DEFM "Retry, Abort?"
DEFB 0
This is just the author's autograph!
DEFM "RZ-DOSv1 special for"
DEFM "magazine DEJA VU!"
DEFM "Rezonance multimedia"
DEFM "group"
;------------------------------; INTERCEPTION ERRORS TR-DOS!!! |
; Are looking for intercepting calls to |
; ROM BASIC 1948 (BIOS) |
;------------------------------; Handle errors:
; Disc error Trc XX sec XX
; Read only Trc XX sec XX
; Break-cont repeats
From top of stack address routines and check whether you need
to replace it.
DOS_error_intercept
POP DE
AND A
LD HL, # 0D6B
SBC HL, DE
Discovery channel 0. Instead, the channel open
window.
JP Z, DOS_window_open
AND A
LD HL, # 0010
SBC HL, DE
Print a character.
JP Z, DOS_write
AND A
LD HL, # 1A1B
SBC HL, DE
Print numbers from the register of 'BC'.
JP Z, DOS_hex_sumbol
AND A
LD HL, # 028E
SBC HL, DE
Just go back to DOS with the established
flags.
JP Z, DOS_return
AND A
LD HL, # 031E
SBC HL, DE
Same as the previous one.
JP Z, DOS_return
AND A
LD HL, # 0333
SBC HL, DE
Poll keys "R", "A", "I".
JP Z, DOS_ask_and_close
AND A
LD HL, # 1B7B
SBC HL, DE
Subroutine call RST8
JP Z, DOS_rst8
Restore the 'HL', 'DE', and procedure calls
from BASIC 48.
PUSH DE
In these variables DOS copies the registers before calling the
procedure.
LD HL, (23810)
LD DE, (23812)
RET
;------------------------------; PRINT NUMBER FROM REGISTER 'BC'
, (NUMBER OF TRACK AND SECTOR)
DOS_hex_sumbol
Print '#' character, since sector number
or track is displayed in hexadecimal
format.
LD A, "#"
CALL DOS_write
Find and print high-order nibble.
LD HL, DOS_fex_sumbol1
LD D, 0
LD E, C
SRL E
SRL E
SRL E
SRL E
ADD HL, DE
LD A, (HL)
CALL DOS_write
Now the younger nibble.
LD A, C
AND # 0F
LD HL, DOS_fex_sumbol1
LD D, 0
LD E, A
ADD HL, DE
LD A, (HL)
CALL DOS_write
RET
DOS_hex_sumbol1
DEFM "0123456789ABCDF"
;------------------------------; POLL KEYBOARD AND CLOSE WINDOW
DOS_ask_and_close
CALL DOS_RAI_ask
CALL DOS_window_close
RET
;------------------------------; RETURN TO DOS WITH INCLUDED
, The Z flag, and C (INSTEAD OF INTERVIEW)
DOS_return
LD A, # 01
ADD A, # FF
RET
;------------------------------; POLL KEYBOARD
DOS_RAI_ask
LD A, # FB
IN A, (# FE)
BIT 3, A
LD A, "R"
RET Z
LD A, # FD
IN A, (# FE)
BIT 0, A
LD A, "A"
RET Z
LD A, # DF
IN A, (# FE)
BIT 2, A
LD A, "I"
RET Z
JR DOS_RAI_ask
;------------------------------; If pressed "BREAK", TO DOS
, Calls the procedure RST8
Substitute sub RST 8. Restore the stack in the 'BC' and (23823)
error code "Break-cont repeats"
DOS_rst8
LD SP, (23827)
LD BC, 20
LD A, C
LD (23823), A
RET
;------------------------------; OPENING DOORS
The window is formed in the middle third of the screen,
height of the four familiarity. DOS_window_open
Save the registers.
PUSH AF
PUSH HL
PUSH DE
PUSH BC
Address of the screen to the routine.
LD HL, # 4802
LD (DOSscr), HL
Copy the contents of the screen to the clipboard and clear the
window.
LD HL, # 4820
LD DE, DOS_bufer
DOS_Wopen1
LD BC, 32 * 3
DOS_Wopen2
LD A, (HL)
LD (HL), 0
LD (DE), A
INC HL
INC DE
DEC BC
LD A, B
OR C
JR NZ, DOS_Wopen2
INC H
LD A, # 20
LD L, A
LD A, 7
AND H
JR NZ, DOS_Wopen1
Same for the field attributes.
LD HL, # 5920
LD BC, 32 * 3
DOS_Wopen3
LD A, (HL)
LD (HL), # 16
LD (DE), A
INC HL
INC DE
DEC BC
LD A, B
OR C
JR NZ, DOS_Wopen3
Restore registers and return.
POP BC
POP DE
POP HL
POP AF
RET
;------------------------------; CLOSE WINDOW
DOS_window_close
Save registers
PUSH AF
PUSH HL
PUSH DE
PUSH BC
Restore the contents of the screen under the window.
LD HL, DOS_bufer
LD DE, # 4820
DOS_Wclose1
LD BC, 32 * 3
LDIR
INC D
LD A, # 20
LD E, A
LD A, 7
AND D
JR NZ, DOS_Wclose1
Same for the field attributes.
LD DE, # 5920
LD BC, 32 * 3
LDIR
Restore registers and return.
POP BC
POP DE
POP HL
POP AF
RET
;------------------------------; PROCEDURE printed characters
; Designed specifically for
; RZ-DOSv1, AND LETS PRINT
; Characters inside third of the screen!
Print a line of text.
DOS_write_line
LD A, (HL)
INC HL
AND A
RET Z
CALL DOS_write
JR DOS_write_line
Print a character. The procedure is simplified and therefore
only prints characters within a third of the screen, because if
there transition to the next one third, then familiarity will
address incorrectly calculated. DOS_write
Save the registers.
PUSH HL
PUSH DE
PUSH BC
Transfer code line?
CP # 0D
JR NZ, DOS_write1
Yes. Put in the 'HL' address familiarity.
LD HL, (DOSscr)
Zeroing the lowest 5 register.
Now the current left-most column.
LD A, L
AND # E0
Add 32 and thus move on to the next line.
ADD A, # 20
Back from the edge of two familiarity.
OR 2
LD L, A
Stored in the variable.
LD (DOSscr), HL
JP DOS_write3
DOS_write1
In the 'HL' character code.
LD L, A
LD H, 0
Multiply by 8.
ADD HL, HL
ADD HL, HL
ADD HL, HL
Add to the character generator address in ROM.
LD DE, # 3C00
ADD HL, DE
We place a 'DE' address familiarity.
LD DE, (DOSscr)
Copy the screen from the ROM 8 lines.
LD B, 8
DOS_write2
LD A, (HL)
LD (DE), A
INC HL
INC D
DJNZ DOS_write2
Go to the next print position.
LD DE, (DOSscr)
INC DE
LD (DOSscr), DE
Restore registers and return.
DOS_write3
POP BC
POP DE
POP HL
RET
;------------------------------; Buffer for SCREEN
DOS_bufer
DEFS 1024,0
The article was written under an informational support of
the book Fedin Pavel Yurevich Complete description + full
disassembler ROM TR-DOS 5.04T (5.03) ". One can only thank him
for his work and recommend the readers of this wonderful book
as a guide to explore the features of the TR-DOS.
Until next time!
-----------------------------------------
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