mirror of https://github.com/bochs-emu/Bochs
70 lines
2.9 KiB
Plaintext
70 lines
2.9 KiB
Plaintext
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Patch name: patch.fdc-read-check-head
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Author: Bryce Denney
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Date: Fri Sep 28 23:20:49 EDT 2001
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RCS Id: $Id: patch.fdc-read-check-head,v 1.2 2001-09-29 03:20:47 bdenney Exp $
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Detailed description:
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This is intended to fix source forge bug 4339945, floppy drive read
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input error checking. The bug report was:
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> When sending the read command to the floppy drive, in one parameter
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> you send the drive number in bit 0, and the head number in bit 2.
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> Later on in the command sequence, you send another byte with the
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> head bit in bit 0. For error-free code, these two head values should
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> be identical, and Bochs doesn't have problems. If they are not equal
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> however, my real floppy drive will not read the disk. Status
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> registers ST0, ST1, and ST2 equal 0x40, 0x04 and 0x00, respectively.
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> The value of ST1 means the sector was not found. Bochs, however,
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> will allow the read to go through and it returns the sector that is
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> under the head given by the second time you submit the head number
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> in the read sequence.
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I don't have any test code, so I'm asking the user to try it out or
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provide some test code.
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Patch was created with:
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cvs diff -u
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Apply patch to what version:
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current cvs (9/28/2001)
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Instructions:
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To patch, go to main bochs directory.
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Type "patch -p0 < THIS_PATCH_FILE".
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----------------------------------------------------------------------
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===================================================================
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RCS file: /cvsroot/bochs/bochs/iodev/floppy.cc,v
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retrieving revision 1.20
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diff -u -r1.20 floppy.cc
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--- iodev/floppy.cc 2001/09/26 17:35:51 1.20
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+++ iodev/floppy.cc 2001/09/29 03:19:31
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@@ -735,6 +735,28 @@
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if (head > 1)
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BX_PANIC(("io: bad head #"));
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+ // check that head number in command[1] bit two matches the head
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+ // reported in the head number field. Real floppy drives are
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+ // picky about this, as reported in SF bug #439945, (Floppy drive
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+ // read input error checking).
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+ if (head != (BX_FD_THIS s.command[1]>>2)&1) {
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+ BX_ERROR(("head number in command[1] doesn't match head field"));
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+ BX_FD_THIS s.result_size = 7;
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+ BX_FD_THIS s.result_index = 0;
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+ BX_FD_THIS s.result[0] = 0x40 | (BX_FD_THIS s.head[drive]<<2) | drive; // abnormal termination
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+ BX_FD_THIS s.result[1] = 0x04; // 0000 0100
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+ BX_FD_THIS s.result[2] = 0x00; // 0000 0000
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+ BX_FD_THIS s.result[3] = BX_FD_THIS s.cylinder[drive];
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+ BX_FD_THIS s.result[4] = BX_FD_THIS s.head[drive];
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+ BX_FD_THIS s.result[5] = BX_FD_THIS s.sector[drive];
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+ BX_FD_THIS s.result[6] = 2; // sector size = 512
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+
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+ BX_FD_THIS s.pending_command = 0;
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+ BX_FD_THIS s.main_status_reg = FD_MS_MRQ | FD_MS_DIO | FD_MS_BUSY;
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+ BX_FD_THIS devices->pic->trigger_irq(6);
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+ return;
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+ }
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+
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if ( BX_FD_THIS s.media_present[drive] == 0 ) {
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// media not in drive, return error
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