Experimental untested MSBSYNC support.

diff --git a/disk.cpp b/disk.cpp
index 4dc7cb32a27497a22ea8f8ec177dd619a280374e..b6ccd49a62f1e800ce9968ae582da314d269c714 100644 (file)
--- a/disk.cpp
+++ b/disk.cpp
@@ -3531,6 +3531,10 @@ static int doreaddma (void)
                        } else {
                                DSKDAT (word);
                                dsklength--;
+#if 0
+                               if (dsklength < 1 && (adkcon & 0x200))
+                                       activate_debugger();
+#endif
                        }
                }
                return 1;
@@ -3574,7 +3578,7 @@ static void wordsync_detected(bool startup)
                        dma_enable = 1;
                INTREQ(0x8000 | 0x1000);
        }
-       if (adkcon & 0x0400) {
+       if (adkcon & 0x0400) { // WORDSYNC
                bitoffset = 15;
        }
 }
@@ -3600,8 +3604,11 @@ static void disk_doupdate_read (drive * drv, int floppybits)
        mfmbuf[7] = 0x4444;
        */
        while (floppybits >= drv->trackspeed) {
+               bool skipbit = false;
+
                if (drv->tracktiming[0])
                        updatetrackspeed (drv, drv->mfmpos);
+
                word <<= 1;
 
                if (!drive_empty (drv)) {
@@ -3610,6 +3617,7 @@ static void disk_doupdate_read (drive * drv, int floppybits)
                        else
                                word |= getonebit (drv->bigmfmbuf, drv->mfmpos);
                }
+
                //write_log (_T("%08X bo=%d so=%d mfmpos=%d dma=%d\n"), (word & 0xffffff), bitoffset, syncoffset, drv->mfmpos, dma_enable);
                if (doreaddma () < 0) {
                        word >>= 1;
@@ -3646,16 +3654,35 @@ static void disk_doupdate_read (drive * drv, int floppybits)
                                }
                        }
                }
-               if ((bitoffset & 7) == 7) {
+
+               // MSBSYNC
+               if (adkcon & 0x200) {
+                       if ((word & 0x0001) == 0 && bitoffset == 0) {
+                               word = 0;
+                               skipbit = true;
+                       }
+                       if ((word & 0x0001) == 0 && bitoffset == 8) {
+                               word >>= 1;
+                               skipbit = true;
+                       }
+               }
+
+               if (!skipbit && (bitoffset & 7) == 7) {
                        dskbytr_val = word & 0xff;
                        dskbytr_val |= 0x8000;
                }
-               if (word == dsksync)
+
+               // WORDSYNC
+               if (!(adkcon & 0x200) && word == dsksync) {
                        wordsync_detected(false);
-               bitoffset++;
-               bitoffset &= 15;
-               floppybits -= drv->trackspeed;
+               }
 
+               if (!skipbit) {
+                       bitoffset++;
+                       bitoffset &= 15;
+               }
+
+               floppybits -= drv->trackspeed;
        }
 }