Re: CD-ROM RECOGNITION

 BBS: Inland Empire Archive
Date: 02-10-93 (11:19)             Number: 235
From: FRANCOIS ROY                 Refer#: NONE
  To: TRENT SHIRLEY                 Recvd: NO  
Subj: Re: CD-ROM RECOGNITION         Conf: (2) Quik_Bas

You can use CALL INTERRUPT to read the ISO-9660 sectors via MSCDEX.  The VTOC
(Volume Table of Contents) is accessible as shown below; I don't have its
structure so can't tell you what the fields mean, but I can betcha no two are
alike... the VTOC is a 2048-byte string; I defined my buffer in CDVTOC with a
length of 4096 because for some reason 2048 gives me String Space Corrupt
errors... the demo routine below prints the first 800 bytes of the VTOC but
you may want to store the whole 2048 bytes as the CD's "fingerprint".

The code snippet below is for QB; QBX far strings need a small alteration.

DECLARE SUB CDVTOC (D$, V$)
DECLARE SUB CDDRIVE (DR$)
   TYPE REGTYPE  ' For CALL INTERRUPT
     AX AS INTEGER
     BX AS INTEGER
     CX AS INTEGER
     DX AS INTEGER
     BP AS INTEGER
     SI AS INTEGER
     DI AS INTEGER
     FL AS INTEGER
     DS AS INTEGER
     ES AS INTEGER
   END TYPE
   DIM SHARED INR AS REGTYPE, OUR AS REGTYPE
   CALL CDDRIVE(D$)
   PRINT "Drive:"; D$
   CALL CDVTOC(D$, V$)
   PRINT LEFT$(V$, 800)
   END

SUB CDDRIVE (DR$) STATIC
    DR$ = STRING$(32, 0)
    INR.AX = &H150D
    INR.BX = SADD(DR$)
    INR.ES = SSEG(DR$)
    CALL InterruptX(&H2F, INR, OUR)
    IF ASC(DR$) = 0 THEN DR$ = "" ELSE DR$ = CHR$(ASC(DR$) + 65) + ":"
END SUB

SUB CDVTOC (D$, V$) STATIC
REM Reads VTOC
    DR$ = STRING$(4096, 0)
    INR.AX = &H1505
    INR.BX = SADD(DR$)
    INR.CX = INSTR("ABCDEFGHIJKLMNOP", LEFT$(D$, 1)) - 1
    INR.DX = 0  ' 1st volume descriptor
    INR.ES = SSEG(DR$)
    CALL InterruptX(&H2F, INR, OUR)
REM AX=1 is normal and indicates a standard vol. descr.
REM AX=15 is 'Invalid Drive' and 21 is 'Not Ready'. 255 means no vol. desc.
    IF OUR.AX > 1 THEN V$ = "Error" + STR$(OUR.AX) ELSE V$ = DR$
END SUB

--- ME2_1104
 * Origin: Out of String Space - the Final Frontier (Fidonet 1:163/506.2)