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mfi: Fix the format thanks to smf's help [O. Galibert]

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This commit is contained in:
Olivier Galibert 2011-09-03 20:50:51 +00:00
parent fd38e72142
commit fcd0950265
2 changed files with 19 additions and 20 deletions
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34
src/lib/formats/mfi_dsk.c
View File

@ -22,11 +22,12 @@
simple "compress" function.
Track data consists of a series of 32-bits lsb-first values
representing magnetic cells. Bits 0-27 indicate the sizes, and bits
28-31 the types. Type can be:
- 0 -> 0-level bit
- 1 -> 1-level bit
- 2 -> weak bit, randomly appears at 0 or 1
representing magnetic cells. Bits 0-27 indicate the sizes, and bit
31 the orientation. Bits 28-30 are currently unused and must be 0.
Remember that the fdcs detect transitions, not absolute levels, so
the actual physical significance of the orientation bit is
arbitrary.
Tracks data is aligned so that the index pulse is at the start,
whether the disk is hard-sectored or not.
@ -97,13 +98,9 @@ UINT32 mfi_format::get_next_edge(const UINT32 *trackbuf, UINT32 cur_cell, UINT32
if(cur_cell == cell_count)
return 200000000;
UINT32 cur_bit = trackbuf[cur_cell] & BIT_MASK;
if(cur_bit == BIT_WEAK)
cur_bit = BIT_0;
cur_cell++;
while(cur_cell != cell_count) {
UINT32 next_bit = trackbuf[cur_cell] & BIT_MASK;
if(next_bit == BIT_WEAK)
next_bit = BIT_0;
if(next_bit != cur_bit)
break;
}
@ -179,37 +176,40 @@ bool mfi_format::load(floppy_image *image)
UINT32 cur_cell = 0;
UINT32 pll_period = 2000;
UINT32 pll_phase = 1000;
UINT32 pll_phase = 0;
for(;;) {
advance(trackbuf, cur_cell, cell_count, pll_phase);
if(cur_cell == cell_count)
break;
if((trackbuf[cur_cell] & BIT_MASK) == BIT_1)
mfm[bit >> 3] |= 0x80 >> (bit & 7);
bit++;
#if 0
printf("%09d: (%d, %09d) - (%d, %09d) - (%d, %09d)\n",
pll_phase,
trackbuf[cur_cell] >> BIT_SHIFT, trackbuf[cur_cell] & TIME_MASK,
trackbuf[cur_cell+1] >> BIT_SHIFT, trackbuf[cur_cell+1] & TIME_MASK,
trackbuf[cur_cell]+2 >> BIT_SHIFT, trackbuf[cur_cell+2] & TIME_MASK);
trackbuf[cur_cell+2] >> BIT_SHIFT, trackbuf[cur_cell+2] & TIME_MASK);
#endif
UINT32 next_edge = get_next_edge(trackbuf, cur_cell, cell_count);
if(next_edge > pll_phase + pll_period) {
// free run
// free run, zero bit
// printf("%09d: %4d - Free run\n", pll_phase, pll_period);
pll_phase += pll_period;
} else {
// Adjust
// Transition in the window, one bit, adjust the period
mfm[bit >> 3] |= 0x80 >> (bit & 7);
INT32 delta = next_edge - (pll_phase + pll_period/2);
// printf("%09d: %4d - Delta = %d\n", pll_phase, pll_period, delta);
// The deltas should be lowpassed, the amplification factor tuned...
pll_period += delta/2;
pll_phase += pll_period;
}
bit++;
}
image->set_track_size(cyl, head, (bit+7)/8);

5
src/lib/formats/mfi_dsk.h
View File

@ -19,12 +19,11 @@ public:
private:
enum {
TIME_MASK = 0x0fffffff,
BIT_MASK = 0xf0000000,
BIT_SHIFT = 28,
BIT_MASK = 0x80000000,
BIT_SHIFT = 31,
BIT_0 = (0 << BIT_SHIFT),
BIT_1 = (1 << BIT_SHIFT),
BIT_WEAK = (2 << BIT_SHIFT)
};
static const char sign[16];