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Groundwork laid for upcoming BACKTRACK support

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This commit is contained in:
Jeff Parsons 2014-12-23 16:02:41 -08:00 • committed by jeffpar
commit 2034428e9f
17 changed files with 5524 additions and 3147 deletions
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17
modules/pcjs/lib/fdc.js
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@ -1104,8 +1104,8 @@ FDC.prototype.copyDrive = function(iDrive)
*
* Also note that in an actual FDC request, drive.nBytes is initialized to the size of a single sector; the extent
* of the entire transfer is actually determined by a count that has been pre-loaded into the DMA controller. The FDC
* isn't even aware of the extent of the transfer, so in the case of a read request, all readByte() can do is return bytes
* until the current track (or, in the case of a multi-track request, the current cylinder) has been exhausted.
* isn't even aware of the extent of the transfer, so in the case of a read request, all readByte() can do is return
* bytes until the current track (or, in the case of a multi-track request, the current cylinder) has been exhausted.
*
* Since seekDrive() is for use with non-DMA requests, we use nBytes to specify the length of the entire transfer.
*
@ -2281,7 +2281,7 @@ FDC.prototype.doFormat = function(drive)
};
/**
* readByte(drive)
* readByte(drive, done)
*
* The following drive properties must have been setup prior to our first call:
*
@ -2301,16 +2301,21 @@ FDC.prototype.doFormat = function(drive)
*
* @this {FDC}
* @param {Object} drive
* @param {function(number,boolean)} done (number is next available byte from drive, or -1 if no more bytes available)
* @param {function(number,boolean,Object,number)} done (number is next available byte from drive, or -1 if no more bytes available)
*/
FDC.prototype.readByte = function(drive, done)
{
var b = -1;
var obj, off; // these variables are purely for BACKTRACK purposes
if (!drive.resCode && drive.disk) {
do {
if (drive.sector) {
if ((b = drive.disk.read(drive.sector, drive.ibSector++)) >= 0)
off = drive.ibSector;
if ((b = drive.disk.read(drive.sector, drive.ibSector++)) >= 0) {
obj = drive.sector;
break;
}
}
/*
* Locate the next sector, and then try reading again.
@ -2328,7 +2333,7 @@ FDC.prototype.readByte = function(drive, done)
this.advanceSector(drive);
} while (true);
}
done(b, false);
done(b, false, obj, off);
};
/**