![]() |
Routines |
Prev: 01507 | Up: Map |
Used by the routine at CLASS_0B.
This entry point is used for all four commands. The value held in T-ADDR, however, distinguishes between the four commands. The first part of the following routine is concerned with the construction of the 'header information' in the work space.
|
||||||||
SAVE_ETC | 01541 | POP AF | Drop the address - SCAN_LOOP. | |||||
01542 | LD A,(23668) | Reduce T-ADDR-lo by 224, giving 0 for SAVE, 1 for LOAD, 2 for VERIFY and 3 for MERGE. | ||||||
01545 | SUB 224 | |||||||
01547 | LD (23668),A | |||||||
01550 | CALL CLASS_0A | Pass the parameters of the 'name' to the calculator stack. | ||||||
01553 | CALL SYNTAX_Z | Jump forward if checking syntax. | ||||||
01556 | JR Z,SA_DATA | |||||||
01558 | LD BC,17 | Allow seventeen locations for the header of a SAVE (T-ADDR-lo=0) but thirty four for the other commands. | ||||||
01561 | LD A,(23668) | |||||||
01564 | AND A | |||||||
01565 | JR Z,SA_SPACE | |||||||
01567 | LD C,34 | |||||||
SA_SPACE | 01569 | RST 48 | The required amount of space is made in the work space. | |||||
01570 | PUSH DE | Copy the start address to the IX register pair. | ||||||
01571 | POP IX | |||||||
01573 | LD B,11 | A program name can have up to ten characters but first enter eleven space characters into the prepared area. | ||||||
01575 | LD A," " | |||||||
SA_BLANK | 01577 | LD (DE),A | ||||||
01578 | INC DE | |||||||
01579 | DJNZ SA_BLANK | |||||||
01581 | LD (IX+1),255 | A null name is 255 only. | ||||||
01585 | CALL STK_FETCH | The parameters of the name are fetched and its length is tested. | ||||||
01588 | LD HL,65526 | This is '-10'. | ||||||
01591 | DEC BC | In effect jump forward if the length of the name is not too long (i.e. no more than ten characters). | ||||||
01592 | ADD HL,BC | |||||||
01593 | INC BC | |||||||
01594 | JR NC,SA_NAME | |||||||
01596 | LD A,(23668) | But allow for the LOADing, VERIFYing and MERGEing of programs (T-ADDR-lo>0) with 'null' names or extra long names. | ||||||
01599 | AND A | |||||||
01600 | JR NZ,SA_NULL | |||||||
Report F - Invalid file name.
|
||||||||
01602 | RST 8 | Call the error handling routine. | ||||||
01603 | DEFB 14 | |||||||
Continue to handle the name of the program.
|
||||||||
SA_NULL | 01604 | LD A,B | Jump forward if the name has a 'null' length. | |||||
01605 | OR C | |||||||
01606 | JR Z,SA_DATA | |||||||
01608 | LD BC,10 | But truncate longer names. | ||||||
The name is now transferred to the work space (second location onwards).
|
||||||||
SA_NAME | 01611 | PUSH IX | Copy the start address to the HL register pair. | |||||
01613 | POP HL | |||||||
01614 | INC HL | Step to the second location. | ||||||
01615 | EX DE,HL | Switch the pointers over and copy the name. | ||||||
01616 | LDIR | |||||||
The many different parameters, if any, that follow the command are now considered. Start by handling 'xxx "name" DATA'.
|
||||||||
SA_DATA | 01618 | RST 24 | Is the present code the token 'DATA'? | |||||
01619 | CP 228 | |||||||
01621 | JR NZ,SA_SCR | Jump if not. | ||||||
01623 | LD A,(23668) | However it is not possible to have 'MERGE name DATA' (T-ADDR-lo=3). | ||||||
01626 | CP 3 | |||||||
01628 | JP Z,REPORT_C | |||||||
01631 | RST 32 | Advance CH-ADD. | ||||||
01632 | CALL LOOK_VARS | Look in the variables area for the array. | ||||||
01635 | SET 7,C | Set bit 7 of the array's name. | ||||||
01637 | JR NC,SA_V_OLD | Jump if handling an existing array. | ||||||
01639 | LD HL,0 | Signal 'using a new array'. | ||||||
01642 | LD A,(23668) | Consider the value in T-ADDR-lo and give an error if trying to SAVE or VERIFY a new array. | ||||||
01645 | DEC A | |||||||
01646 | JR Z,SA_V_NEW | |||||||
Report 2 - Variable not found.
|
||||||||
01648 | RST 8 | Call the error handling routine. | ||||||
01649 | DEFB 1 | |||||||
Continue with the handling of an existing array.
|
||||||||
SA_V_OLD | 01650 | JP NZ,REPORT_C | Note: this fails to exclude simple strings. | |||||
01653 | CALL SYNTAX_Z | Jump forward if checking syntax. | ||||||
01656 | JR Z,SA_DATA_1 | |||||||
01658 | INC HL | Point to the 'low length' of the variable. | ||||||
01659 | LD A,(HL) | The low length byte goes into the work space, followed by the high length byte. | ||||||
01660 | LD (IX+11),A | |||||||
01663 | INC HL | |||||||
01664 | LD A,(HL) | |||||||
01665 | LD (IX+12),A | |||||||
01668 | INC HL | Step past the length bytes. | ||||||
The next part is common to both 'old' and 'new' arrays. Note: syntax path error.
|
||||||||
SA_V_NEW | 01669 | LD (IX+14),C | Copy the array's name. | |||||
01672 | LD A,1 | Assume an array of numbers. | ||||||
01674 | BIT 6,C | Jump if it is so. | ||||||
01676 | JR Z,SA_V_TYPE | |||||||
01678 | INC A | It is an array of characters. | ||||||
SA_V_TYPE | 01679 | LD (IX+0),A | Save the 'type' in the first location of the header area. | |||||
The last part of the statement is examined before joining the other pathways.
|
||||||||
SA_DATA_1 | 01682 | EX DE,HL | Save the pointer in DE. | |||||
01683 | RST 32 | Is the next character a ')'? | ||||||
01684 | CP ")" | |||||||
01686 | JR NZ,SA_V_OLD | Give report C if it is not. | ||||||
01688 | RST 32 | Advance CH-ADD. | ||||||
01689 | CALL CHECK_END | Move on to the next statement if checking syntax. | ||||||
01692 | EX DE,HL | Return the pointer to the HL register pair before jumping forward. (The pointer indicates the start of an existing array's contents.) | ||||||
01693 | JP SA_ALL | |||||||
Now consider 'SCREEN$'.
|
||||||||
SA_SCR | 01696 | CP 170 | Is the present code the token SCREEN$? | |||||
01698 | JR NZ,SA_CODE | Jump if not. | ||||||
01700 | LD A,(23668) | However it is not possible to have 'MERGE name SCREEN$' (T-ADDR-lo=3). | ||||||
01703 | CP 3 | |||||||
01705 | JP Z,REPORT_C | |||||||
01708 | RST 32 | Advance CH-ADD. | ||||||
01709 | CALL CHECK_END | Move on to the next statement if checking syntax. | ||||||
01712 | LD (IX+11),0 | The display area and the attribute area occupy 6912 locations and these locations start at 16384; these details are passed to the header area in the work space. | ||||||
01716 | LD (IX+12),27 | |||||||
01720 | LD HL,16384 | |||||||
01723 | LD (IX+13),L | |||||||
01726 | LD (IX+14),H | |||||||
01729 | JR SA_TYPE_3 | Jump forward. | ||||||
Now consider 'CODE'.
|
||||||||
SA_CODE | 01731 | CP 175 | Is the present code the token 'CODE'? | |||||
01733 | JR NZ,SA_LINE | Jump if not. | ||||||
01735 | LD A,(23668) | However it is not possible to have 'MERGE name CODE' (T-ADDR-lo=3). | ||||||
01738 | CP 3 | |||||||
01740 | JP Z,REPORT_C | |||||||
01743 | RST 32 | Advance CH-ADD. | ||||||
01744 | CALL PR_ST_END | Jump forward if the statement has not finished. | ||||||
01747 | JR NZ,SA_CODE_1 | |||||||
01749 | LD A,(23668) | However it is not possible to have 'SAVE name CODE' (T-ADDR-lo=0) by itself. | ||||||
01752 | AND A | |||||||
01753 | JP Z,REPORT_C | |||||||
01756 | CALL USE_ZERO | Put a zero on the calculator stack - for the 'start'. | ||||||
01759 | JR SA_CODE_2 | Jump forward. | ||||||
Look for a 'starting address'.
|
||||||||
SA_CODE_1 | 01761 | CALL CLASS_06 | Fetch the first number. | |||||
01764 | RST 24 | Is the present character a comma? | ||||||
01765 | CP "," | |||||||
01767 | JR Z,SA_CODE_3 | Jump if it is - the number was a 'starting address'. | ||||||
01769 | LD A,(23668) | However refuse 'SAVE name CODE' that does not have a 'start' and a 'length' (T-ADDR-lo=0). | ||||||
01772 | AND A | |||||||
01773 | JP Z,REPORT_C | |||||||
SA_CODE_2 | 01776 | CALL USE_ZERO | Put a zero on the calculator stack - for the 'length'. | |||||
01779 | JR SA_CODE_4 | Jump forward. | ||||||
Fetch the 'length' as it was specified.
|
||||||||
SA_CODE_3 | 01781 | RST 32 | Advance CH-ADD. | |||||
01782 | CALL CLASS_06 | Fetch the 'length'. | ||||||
The parameters are now stored in the header area of the work space.
|
||||||||
SA_CODE_4 | 01785 | CALL CHECK_END | But move on to the next statement now if checking syntax. | |||||
01788 | CALL FIND_INT2 | Compress the 'length' into the BC register pair and store it. | ||||||
01791 | LD (IX+11),C | |||||||
01794 | LD (IX+12),B | |||||||
01797 | CALL FIND_INT2 | Compress the 'starting address' into the BC register pair and store it. | ||||||
01800 | LD (IX+13),C | |||||||
01803 | LD (IX+14),B | |||||||
01806 | LD H,B | Transfer the 'pointer' to the HL register pair as usual. | ||||||
01807 | LD L,C | |||||||
'SCREEN$' and 'CODE' are both of type 3.
|
||||||||
SA_TYPE_3 | 01808 | LD (IX+0),3 | Enter the 'type' number. | |||||
01812 | JR SA_ALL | Rejoin the other pathways. | ||||||
Now consider 'LINE' and 'no further parameters'.
|
||||||||
SA_LINE | 01814 | CP 202 | Is the present code the token 'LINE'? | |||||
01816 | JR Z,SA_LINE_1 | Jump if it is. | ||||||
01818 | CALL CHECK_END | Move on to the next statement if checking syntax. | ||||||
01821 | LD (IX+14),128 | When there are no further parameters, 128 is entered. | ||||||
01825 | JR SA_TYPE_0 | Jump forward. | ||||||
Fetch the 'line number' that must follow 'LINE'.
|
||||||||
SA_LINE_1 | 01827 | LD A,(23668) | However only allow 'SAVE name LINE number' (T-ADDR-lo=0). | |||||
01830 | AND A | |||||||
01831 | JP NZ,REPORT_C | |||||||
01834 | RST 32 | Advance CH-ADD. | ||||||
01835 | CALL CLASS_06 | Pass the number to the calculator stack. | ||||||
01838 | CALL CHECK_END | Move on to the next statement if checking syntax. | ||||||
01841 | CALL FIND_INT2 | Compress the 'line number' into the BC register pair and store it. | ||||||
01844 | LD (IX+13),C | |||||||
01847 | LD (IX+14),B | |||||||
'LINE' and 'no further parameters' are both of type 0.
|
||||||||
SA_TYPE_0 | 01850 | LD (IX+0),0 | Enter the 'type' number. | |||||
The parameters that describe the program, and its variables, are found and stored in the header area of the work space.
|
||||||||
01854 | LD HL,(23641) | The pointer to the end of the variables area (E-LINE). | ||||||
01857 | LD DE,(23635) | The pointer to the start of the BASIC program (PROG). | ||||||
01861 | SCF | Now perform the subtraction to find the length of the 'program + variables'; store the result. | ||||||
01862 | SBC HL,DE | |||||||
01864 | LD (IX+11),L | |||||||
01867 | LD (IX+12),H | |||||||
01870 | LD HL,(23627) | Repeat the operation but this time storing the length of the 'program' only (VARS-PROG). | ||||||
01873 | SBC HL,DE | |||||||
01875 | LD (IX+15),L | |||||||
01878 | LD (IX+16),H | |||||||
01881 | EX DE,HL | Transfer the 'pointer' to the HL register pair as usual. | ||||||
In all cases the header information has now been prepared.
The routine continues with the first task being to separate SAVE from LOAD, VERIFY and MERGE.
|
||||||||
SA_ALL | 01882 | LD A,(23668) | Jump forward when handling a SAVE command (T-ADDR-lo=0). | |||||
01885 | AND A | |||||||
01886 | JP Z,SA_CONTRL | |||||||
In the case of a LOAD, VERIFY or MERGE command the first seventeen bytes of the 'header area' in the work space hold the prepared information, as detailed above; and it is now time to fetch a 'header' from the tape.
|
||||||||
01889 | PUSH HL | Save the 'destination' pointer. | ||||||
01890 | LD BC,17 | Form in the IX register pair the base address of the 'second header area'. | ||||||
01893 | ADD IX,BC | |||||||
Now enter a loop, leaving it only when a 'header' has been LOADed.
|
||||||||
LD_LOOK_H | 01895 | PUSH IX | Make a copy of the base address. | |||||
01897 | LD DE,17 | LOAD seventeen bytes. | ||||||
01900 | XOR A | Signal 'header'. | ||||||
01901 | SCF | Signal 'LOAD'. | ||||||
01902 | CALL LD_BYTES | Now look for a header. | ||||||
01905 | POP IX | Retrieve the base address. | ||||||
01907 | JR NC,LD_LOOK_H | Go round the loop until successful. | ||||||
The new 'header' is now displayed on the screen but the routine will only proceed if the 'new' header matches the 'old' header.
|
||||||||
01909 | LD A,254 | Ensure that channel 'S' is open. | ||||||
01911 | CALL CHAN_OPEN | |||||||
01914 | LD (IY+82),3 | Set the scroll counter (SCR-CT). | ||||||
01918 | LD C,128 | Signal 'names do not match'. | ||||||
01920 | LD A,(IX+0) | Compare the 'new' type against the 'old' type. | ||||||
01923 | CP (IX-17) | |||||||
01926 | JR NZ,LD_TYPE | Jump if the 'types' do not match. | ||||||
01928 | LD C,246 | But if they do, signal 'ten characters are to match'. | ||||||
LD_TYPE | 01930 | CP 4 | Clearly the 'header' is nonsense if 'type 4 or more'. | |||||
01932 | JR NC,LD_LOOK_H | |||||||
The appropriate message - 'Program: ', 'Number array: ', 'Character array: ' or 'Bytes: ' is printed.
|
||||||||
01934 | LD DE,2496 | The base address of the message block. | ||||||
01937 | PUSH BC | Save the C register whilst the appropriate message is printed. | ||||||
01938 | CALL PO_MSG | |||||||
01941 | POP BC | |||||||
The 'new name' is printed and as this is done the 'old' and the 'new' names are compared.
|
||||||||
01942 | PUSH IX | Make the DE register pair point to the 'new name' and the HL register pair to the 'old name'. | ||||||
01944 | POP DE | |||||||
01945 | LD HL,65520 | |||||||
01948 | ADD HL,DE | |||||||
01949 | LD B,10 | Ten characters are to be considered. | ||||||
01951 | LD A,(HL) | Jump forward if the match is to be against an actual name. | ||||||
01952 | INC A | |||||||
01953 | JR NZ,LD_NAME | |||||||
01955 | LD A,C | But if the 'old name' is 'null' then signal 'ten characters already match'. | ||||||
01956 | ADD A,B | |||||||
01957 | LD C,A | |||||||
A loop is entered to print the characters of the 'new name'. The name will be accepted if the 'counter' reaches zero, at least.
|
||||||||
LD_NAME | 01958 | INC DE | Consider each character of the 'new name' in turn. | |||||
01959 | LD A,(DE) | |||||||
01960 | CP (HL) | Match it against the appropriate character of the 'old name'. | ||||||
01961 | INC HL | |||||||
01962 | JR NZ,LD_CH_PR | Do not count it if it does not does not match. | ||||||
01964 | INC C | |||||||
LD_CH_PR | 01965 | RST 16 | Print the 'new' character. | |||||
01966 | DJNZ LD_NAME | Loop for ten characters. | ||||||
01968 | BIT 7,C | Accept the name only if the counter has reached zero. | ||||||
01970 | JR NZ,LD_LOOK_H | |||||||
01972 | LD A,13 | Follow the 'new name' with a 'carriage return'. | ||||||
01974 | RST 16 | |||||||
The correct header has been found and the time has come to consider the three commands LOAD, VERIFY, and MERGE separately.
|
||||||||
01975 | POP HL | Fetch the pointer. | ||||||
01976 | LD A,(IX+0) | 'SCREEN$' and 'CODE' are handled with VERIFY. | ||||||
01979 | CP 3 | |||||||
01981 | JR Z,VR_CONTRL | |||||||
01983 | LD A,(23668) | Jump forward if using a LOAD command (T-ADDR-lo=1). | ||||||
01986 | DEC A | |||||||
01987 | JP Z,LD_CONTRL | |||||||
01990 | CP 2 | Jump forward if using a MERGE command; continue into VR_CONTRL with a VERIFY command. | ||||||
01992 | JP Z,ME_CONTRL |
Prev: 01507 | Up: Map |