Date: Wed, 27 Nov 2002 17:03:39 -0500
To: Willard Goosey 
From: Rodney V Hamilton 
Date: Wed, 27 Nov 2002 17:03:39 -0500
Subject: Re: IDE errata and fixes


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* Copy LSN0 stuff into drive table
* Entry: X=ptr to 256 byte buffer containing LSN0 Sector.
* Exit: X,D is destroyed
CpyDrvTb pshs  y              Save path desc. ptr
         ldy   PD.DTB,y       Get drive table ptr from path desc
         pshs  y              save drive table ptr
         lda   #DD.SIZ
LSN0Cp   ldb   ,x+
         stb   ,y+
         deca  
         bne   LSN0Cp
* If the drive table's DD.TOT value is zero, OS9 reads no data!
* This can happen if the LSN0 sector starts with three 00 bytes.
* To fix, check for DD.TOT==0 and force nonzero value if so.
         puls  x,y            restore drive table & path desc ptrs
         ldd   ,x             does table DD.TOT==0?
         bne   DrvTbOK
         orb   2,x
         bne   DrvTbOK
         dec   ,x             yes, set msb to $FF
DrvTbOK  rts

         use   ccide16.2.a
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