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https://github.com/SEPPDROID/Digital-Research-Source-Code.git
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304 lines
8.3 KiB
C
304 lines
8.3 KiB
C
/****************************************************************
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* *
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* CP/M-68K BDOS Disk Utilities Module *
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* *
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* This module contains the miscellaneous utilities *
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* for manipulating the disk in CP/M-68K. Included are: *
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* *
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* dirscan() - general purpose dir scanning *
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* setaloc() - set bit in allocation vector *
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* clraloc() - clear bit in allocation vector *
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* getaloc() - get free allocation block *
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* dchksum() - directory checksum calculator *
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* dir_rd() - read directory sector *
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* dir_wr() - write directory sector *
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* rdwrt() - read/write disk sector *
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* *
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* *
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* Configured for Alcyon C on the VAX *
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* *
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****************************************************************/
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#include "bdosinc.h" /* Standard I/O declarations */
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#include "bdosdef.h" /* Type and structure declarations for BDOS */
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#include "pktio.h" /* Packet I/O definitions */
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/* declare external functions and variables */
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EXTERN UWORD do_phio(); /* external physical disk I/O routine */
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EXTERN UWORD error(); /* external error routine */
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EXTERN UWORD log_dsk; /* logged-on disk vector */
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EXTERN UWORD ro_dsk; /* read-only disk vector */
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EXTERN UWORD crit_dsk; /* critical disk vector */
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UBYTE dchksum();
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/**********************
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* read/write routine *
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**********************/
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UWORD rdwrt(secnum, dma, parm)
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/* General disk sector read/write routine */
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/* It simply sets up a I/O packet and sends it to do_phio */
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LONG secnum; /* logical sector number to read/write */
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UBYTE *dma; /* dma address */
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REG WORD parm; /* 0 for read, write parm + 1 for write */
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{
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struct iopb rwpkt;
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BSETUP
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rwpkt.devnum = GBL.curdsk; /* disk to read/write */
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if (parm)
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{
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rwpkt.iofcn = (BYTE)write; /* if parm non-zero, we're doing a write */
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rwpkt.ioflags = (BYTE)(parm-1); /* pass write parm */
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if ( ro_dsk & (1 << (rwpkt.devnum)) ) error(4);
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/* don't write on read-only disk */
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}
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else
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{
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rwpkt.iofcn = (BYTE)read;
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rwpkt.ioflags = (BYTE)0;
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}
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rwpkt.devadr = secnum; /* sector number */
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rwpkt.xferadr = dma; /* dma address */
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/* parameters that are currently not used by do_phio
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rwpkt.devtype = disk;
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rwpkt.xferlen = 1;
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*/
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rwpkt.infop = GBL.dphp; /* pass ptr to dph */
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while ( do_phio(&rwpkt) )
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if ( error( parm ? 1 : 0 ) ) break;
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return(0);
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}
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/***************************
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* directory read routine *
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***************************/
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UWORD dir_rd(secnum)
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WORD secnum;
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{
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BSETUP
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return( rdwrt((LONG)secnum, GBL.dirbufp, 0) );
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}
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/****************************
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* directory write routine *
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****************************/
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UWORD dir_wr(secnum)
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REG WORD secnum;
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{
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REG UWORD rtn;
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BSETUP
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rtn = rdwrt( (LONG)secnum, GBL.dirbufp, 2);
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if ( secnum < (GBL.parmp)->cks )
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*((GBL.dphp)->csv + secnum) = dchksum();
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return(rtn);
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}
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/*******************************
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* directory checksum routine *
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*******************************/
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UBYTE dchksum()
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/* Compute checksum over one directory sector */
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/* Note that this implementation is dependant on the representation */
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/* of a LONG and is therefore not very portable. But it's fast */
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{
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REG LONG *p; /* local temp variables */
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REG LONG lsum;
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REG WORD i;
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BSETUP
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p = GBL.dirbufp; /* point to directory buffer */
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lsum = 0;
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i = SECLEN / (sizeof lsum);
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do
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{
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lsum += *p++; /* add next 4 bytes of directory */
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i -= 1;
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} while (i);
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lsum += (lsum >> 16);
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lsum += (lsum >> 8);
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return( (UBYTE)(lsum & 0xff) );
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}
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/************************
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* dirscan entry point *
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************************/
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UWORD dirscan(funcp, fcbp, parms)
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BOOLEAN (*funcp)(); /* funcp is a pointer to a Boolean function */
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REG struct fcb *fcbp; /* fcbp is a pointer to a fcb */
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REG UWORD parms; /* parms is 16 bit set of bit parameters */
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/* Parms & 1 = 0 to start at beginning of dir, 1 to continue from last */
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/* Parms & 2 = 0 to stop when *funcp is true, 1 to go until end */
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/* Parms & 4 = 0 to check the dir checksum, 1 to store new checksum */
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/* Parms & 8 = 0 to stop at hiwater, 1 to go until end of directory */
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#define continue 1
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#define full 2
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#define initckv 4
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#define pasthw 8
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{
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REG UWORD i; /* loop counter */
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REG struct dpb *dparmp; /* pointer to disk parm block */
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REG UWORD dirsec; /* sector number we're working on */
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REG UWORD rtn; /* return value */
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REG UBYTE *p; /* scratch pointer */
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REG UWORD bitvec; /* disk nmbr represented as a vector */
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BSETUP
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dparmp = GBL.parmp; /* init ptr to dpb */
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rtn = 255; /* assume it doesn't work */
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i = ( (parms & continue) ? GBL.srchpos + 1 : 0 );
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while ( (parms & pasthw) || (i <= ((GBL.dphp)->hiwater + 1)) )
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{ /* main directory scanning loop */
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if ( i > dparmp->drm ) break;
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if ( ! (i & 3) )
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{ /* inside loop happens when we need to
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read another directory sector */
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retry: dirsec = i >> 2;
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dir_rd(dirsec); /* read the directory sector */
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if ( dirsec < (dparmp->cks) ) /* checksumming on this sector? */
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{
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p = ((GBL.dphp)->csv) + dirsec;
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/* point to checksum vector byte */
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if (parms & initckv) *p = dchksum();
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else if (*p != dchksum())
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{ /* checksum error! */
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(GBL.dphp)->hiwater = dparmp->drm; /* reset hi water */
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bitvec = 1 << (GBL.curdsk);
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if (crit_dsk & bitvec) /* if disk in critical mode */
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ro_dsk |= bitvec; /* then set it to r/o */
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else
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{
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log_dsk &= ~bitvec; /* else log it off */
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seldsk(GBL.curdsk); /* and re-select it */
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goto retry; /* and re-do current op */
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}
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}
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}
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}
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GBL.srchpos = i;
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if ( (*funcp)(fcbp, (GBL.dirbufp) + (i&3), i) )
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/* call function with parms of (1) fcb ptr,
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(2) pointer to directory entry, and
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(3) directory index */
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{
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if (parms & full) rtn = 0; /* found a match, but keep going */
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else return(i & 3); /* return directory code */
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}
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i += 1;
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}
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return(rtn);
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}
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/****************************************
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* Routines to manage allocation vector *
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* setaloc() *
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* clraloc() *
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* getaloc() *
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****************************************/
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setaloc(bitnum)
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/* Set bit in allocation vector */
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REG UWORD bitnum;
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{
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BSETUP
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if (bitnum >= 0 && bitnum <= (GBL.parmp)->dsm)
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*((GBL.dphp)->alv + (bitnum>>3)) |= 0x80 >> (bitnum & 7);
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}
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clraloc(bitnum)
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/* Clear bit in allocation vector */
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REG UWORD bitnum;
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{
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BSETUP
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if (bitnum > 0 && bitnum <= (GBL.parmp)->dsm)
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*((GBL.dphp)->alv + (bitnum>>3)) &= ~(0x80 >> (bitnum & 7));
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}
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UWORD chkaloc(i)
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/* Check bit i in allocation vector */
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/* Return non-zero if block free, else return zero */
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REG UWORD i;
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{
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BSETUP
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return( ~(*( (GBL.dphp)->alv + (i >> 3) )) & (0x80 >> (i&7)) );
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}
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UWORD getaloc(leftblk)
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/* Get a free block in the file system and set the bit in allocation vector */
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/* It is passed the block number of the last block allocated to the file */
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/* It tries to allocate the block closest to the block that was passed */
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REG UWORD leftblk;
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{
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REG UWORD blk; /* block number to allocate */
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REG UWORD rtblk; /* high block number to try */
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REG UWORD diskmax; /* # bits in alv - 1 */
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BSETUP
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LOCK /* need to lock the file system while messing
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with the allocation vector */
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diskmax = (GBL.parmp)->dsm;
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/* get disk max field from dpb */
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rtblk = leftblk;
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blk = ~0; /* -1 returned if no free block found */
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while (leftblk || rtblk < diskmax)
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{
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if (leftblk)
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if (chkaloc(--leftblk))
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{
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blk = leftblk;
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break;
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}
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if (rtblk < diskmax)
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if (chkaloc(++rtblk))
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{
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blk = rtblk;
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break;
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}
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}
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if (blk != ~0) setaloc(blk);
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UNLOCK
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return(blk);
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}
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UNLOCK
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return(blk);
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}
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UNLOCK
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return(blk);
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}
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