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In the example above, we will choose LENGTH, FEED, TITLE, PROMPT, and XLATE parameter words for the options 1-5. We will also abbreviate these as L, F, T, P, and X. Your application's documentation must fully explain the purpose of the parameters. A typical command line entry could be: URPROG (length=132,title="Program Guide",xlate=x'0e00') The command line could just as easily have been entered as: URPROG (t="Program Guide",x=x'0e00',l=132) Note that not only are abbreviations used, but the order of appearance in the command line is irrelevant. Also note that parentheses enclose the command line parameters; however, the closing parenthesis is not required. You can take some liberties with the string and hexadecimal syntax. Hexadecimal entries can drop the closing single quote. Strings are considered terminated by any value less than SPACE. Thus, a closing carriage return validly terminates a string. This leeway permits entry of such command lines as: URPROG (t="Program Guide URPROG (x=x'0e00,t="Program Guide You're saying there must be a catch. How can @PARAM do all that? Easy - you must follow some rules and implement some coding in your program. Not very much coding is required, though. When you execute a command line, the command interpreter is activated (@CMNDI ). If a LIBRARY name is specified, the system's library module is activated. If a program name is entered (the system first tries a default extension of /CMD if the user does not supply one) the program will be loaded and transfer will be performed to the program's transfer address which is located at the end of the load module (following the X'0202'). When control is passed to the program, register pair HL contain the address of the first non-blank character following the program name entered. If @PARAM is requested, it will search the command line for a parameter string left parenthesis starting from the address pointed to by HL. It will ignore blanks while it looks for the "("; however, if it finds a non-blank character other than "(", it will immediately return. If there are going to be additional entries, such as file specifications, on the command line preceding possible parameters, these must be parsed first by your program before issuing the @PARAM SVC. The prologue of URPROG might go something like this: URPROG PUSH HL ;Hang on to INBUF$ pointer LD HL,HELLO$ ;Point to hello message LD A,@DSPLY ;Display message to screen RST 40 POP HL ;Recover INBUF$ pointer LD DE,PRMTBL$ ;Point to parameter table LD A,@PARAM ;Go parse all of the parms RST 40 JP NZ,PRMERR ;Go to error handler if bad entry . . ;The rest of URPROG . HELLO$ DB 10,'Some friendly message',CR ;*=*=* ; This is the parameter table. Note its entries are ; all 6-characters in width. The address specified by ; the parameter vector follows each parameter "word". ; In addition, the table is ended with a zero byte. ;*=*=* PRMTBL$ DB 'LENGTH' ;Length parameter DW LPARM+1 DB 'L ' 8-31
DW LPARM+1 DB 'FEED ' ;Line feed parameter DW FPARM+1 DB 'F ' DW FPARM+1 DB 'TITLE ' ;Title parameter DW TPARM+1 DB 'T ' DW TPARM+1 DB 'PROMPT' ;Prompt parameter DW PPARM+1 DB 'P ' DW PPARM+1 DB 'XLATE ' ;Translate parameter DW XPARM+1 DB 'X ' DW XPARM+1 NOP ;This is the ending zero byte The PRMTBL$ is going to be structured similarly for all tables. The convention used of specifying the address vector as "LABEL+1" will become immediately obvious once you inspect the method of using the result in URPROG. As an aside, let's look at two conventions of referencing the second byte of a three-byte instruction. METHOD1 LD (LABEL+1),HL ;Load HL into the "nn" field . . . LABEL LD BC,0 ;P/u the value loaded METHOD2 LD (LABEL),HL ;Load HL into the "nn" field . . . LD BC,0 ;P/u the value loaded LABEL EQU $-2 ;The "nn" field is 2-bytes back The first method will be used to illustrate parameter table vector addresses in this appendix section. Use the method you are most comfortable with. It is suggested that you choose one technique and use it exclusively throughout a program. Otherwise you will find yourself getting into trouble as you forget which method you were using. Now that the @PARAM system function has parsed the entered command line, how do we utilize the "values" it interpreted while still supporting our defaults and conditions? Well, bear in mind that if the user has not entered a parameter word, nothing will be entered by @PARAM into the address vector specified by the parameter table. Therefore, an initial condition can be supplied in the coding. Also, the initial value coded will be dependent on just what condition you want the default to be. Let's see how this would work. . . ;Some front end code . ;*=*=* ; Here is where we pick up the length parameter. Note ; that it is initialized to 80 if there is no user entry ;*=*=* LPARM LD BC,80 ;Pick up the entry INC B ;Test hi-order for zero DEC B ;It must be zero for range check JP NZ,LBAD ;Bad length if range >255 LD A,C ;P/u the lo-order length 8-32
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MISOSYS, INC. The Programmer's Guid
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1. Introduction Many thousands of u
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language (i.e. BASIC, C, PASCAL, ..
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NAME START END DESCRIPTION LOWCORE
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ackup utility provides exceptional
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3. Device Input/Output Interfacing
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3.2.2 VECTOR Field - This field in
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FILTER *PR USING *S0 the operating
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===================================
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===================================
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ENTRY JR BEGIN ;Branch around linka
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DATA1 EQU $-DATA$ DB 0 ;Data storag
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Offset Contents +0 Contains the las
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image of the serial port UART statu
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called TRACKs. Each track is then d
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The DCT contains the information re
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accessed a single-sided diskette, t
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containing the disk's directory. Th
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Command Purpose RESTORE Recalibrate
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available from Logical Systems, Inc
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exceeds this capacity, then it must
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is two physical cylinders. Although
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5. The DOS Directory Structure 5.1
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===================================
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5.2.8 PACK NAME - This field conta
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The position of a file's hash code
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5.4 THE DIRECTORY RECORD STRUCTURE
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Bit 3 Specifies the visibility; if
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the first granule in use is the sec
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travels the turnpike. In this manne
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The @FSPEC SVC will transfer the fi
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A high level language permits you t
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does exist, @RENAME should return e
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Next, it would be very useful if th
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LD HL,FCBX+9 ;Point to the LRL fiel
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operating system for such a purpose
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position where the last character i
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ecord. If a file has more than four
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DE Contains a pointer to the File C
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@RENAM SVC-56 Rename a file on disk
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@FNAME SVC-80 Obtain filespec given
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@WRSEC SVC-53 Write a disk sector @
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7.6 SUPERVISOR CALL DETAILS 7.6.1 @
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Note: @EXIT in SYS1 automatically r
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7.6.10 @CLOSE SVC-60 This SVC will
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7.6.18 @DCSTAT SVC-40 This SVC pass
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Directory to Buffer Entry: B 1; Fun
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7.6.31 @FLAGS$ SVC-101 This SVC wil
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NFLAG$ This "network" flag is used
Page 99 and 100: 7.6.32 @FNAME SVC-80 This SVC will
Page 101 and 102: 7.6.40 @HEX8 SVC-98 This SVC will c
Page 103 and 104: 7.6.48 @KLTSK SVC-32 This SVC will
Page 105 and 106: 7.6.57 @OPEN SVC-59 This SVC will o
Page 107 and 108: Registers Affected: AF, BC. Entry:
Page 109 and 110: 0-14 FILENAME/EXT:D - left justifie
Page 111 and 112: 7.6.71 @REMOV SVC-57 This SVC will
Page 113 and 114: Entry: DE A pointer to the FCB cont
Page 115 and 116: Exit: A Error return code, if any.
Page 117 and 118: CURSOR CHARACTER Registers Affected
Page 119 and 120: Exit: A Will contain the error code
Page 121 and 122: esident routine into its execution
Page 123 and 124: CKPAWS LD A,@FLAGS$ ;Get Flags poin
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Page 127 and 128: The TYPE=0A indicates that it is th
Page 129 and 130: Error 08: Device not available A re
Page 131 and 132: Error 28: End of file encountered T
Page 133 and 134: 8.5 HEADER PROTOCOL OF MEMORY MODUL
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Page 137 and 138: LD (IX+2),15 JR TASKA By firmly und
Page 139 and 140: 8.7.3 Details of Low Memory Page 2
Page 141 and 142: actual bank switching. As previousl
Page 143 and 144: set. Thus, the Z-flag will be indic
Page 145 and 146: 8.10 SYSTEM DISK BOOT TRACK The ope
Page 147 and 148: 14 DEBUG 72 PURGE 1B VERIFY 71 DUMP
Page 149: 8.13 USING @PARAM The @PARAM SuperV
Page 153 and 154: ;*=*=* PPARM LD BC,0 ;Zero because
Page 155 and 156: 8.14 TRAP Filter Illustrated ;TRAP/
Page 157 and 158: 8.15 SLASH0 Filter Illustrated ;SLA
Page 159 and 160: 8.16 DMP-500 BOLDFACE Filter Illust
Page 161 and 162: NOMEM$ DB 'High memory is not avail
Page 163 and 164: @ @ABORT..........7-2, 7-4, 7-8, 7-
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