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Reintroduces delay bit, reverses phase.

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There are stray columns of errors, but otherwise this is almost correct.
This commit is contained in:
Thomas Harte 2020-11-22 11:06:14 -05:00
parent fca48e4b66
commit 8fae74f93e
1 changed files with 18 additions and 14 deletions
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32
Machines/Apple/AppleIIgs/Video.cpp
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@ -70,6 +70,14 @@ VideoBase::VideoBase() :
++ntsc_shift_lookup_[c];
}
// If b0 and b4 disagreed, use the top part. That means that
// there was a diference, but the maximum wait time for new
// data was hit.
if(!ntsc_shift_lookup_[c]) {
ntsc_shift_lookup_[c] = 4;
}
// Note in case bit packing becomes desirable:
// If no incompatibilities were found then the low four bits are identical
// to the top four; can just leave the lookup at a shift of 0 as 0 == 4.
}
@ -484,18 +492,14 @@ uint16_t *VideoBase::output_high_resolution(uint16_t *target, int start, int end
// Just append new bits, doubled up (and possibly delayed).
// TODO: I can kill the conditional here. Probably?
// if(source & high_resolution_mask_ & 0x80) {
// ntsc_shift_ |= doubled_source << 5;
// } else {
// ntsc_shift_ = (ntsc_shift_ & 0xf) | (doubled_source << 4) | ((doubled_source << 5) & 0x80000);
// }
// TODO: reintroduce delay bit. Delay bit should: (i) hold existing bit; and (ii) store top bit for potential
// delay into the next word.
ntsc_shift_ |= doubled_source << 4;
if(source & high_resolution_mask_ & 0x80) {
ntsc_shift_ |= (doubled_source << 5) | ((ntsc_shift_ & 0x08) << 1);
} else {
ntsc_shift_ = (ntsc_shift_ & 0xf) | (doubled_source << 4);
}
// TODO: initial state?
target = output_shift(target, (2 + (c * 14)) & 3);
target = output_shift(target, ((c * 14)) & 3);
}
return target;
@ -507,16 +511,16 @@ uint16_t *VideoBase::output_shift(uint16_t *target, int phase) const {
0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf
},
{
0x0, 0x8, 0x1, 0x9, 0x2, 0xa, 0x3, 0xb,
0x4, 0xc, 0x5, 0xd, 0x6, 0xe, 0x7, 0xf
0x0, 0x2, 0x4, 0x6, 0x8, 0xa, 0xc, 0xe,
0x1, 0x3, 0x5, 0x7, 0x9, 0xb, 0xd, 0xf
},
{
0x0, 0x4, 0x8, 0xc, 0x1, 0x5, 0x9, 0xd,
0x2, 0x6, 0xa, 0xe, 0x3, 0x7, 0xb, 0xf
},
{
0x0, 0x2, 0x4, 0x6, 0x8, 0xa, 0xc, 0xe,
0x1, 0x3, 0x5, 0x7, 0x9, 0xb, 0xd, 0xf
0x0, 0x8, 0x1, 0x9, 0x2, 0xa, 0x3, 0xb,
0x4, 0xc, 0x5, 0xd, 0x6, 0xe, 0x7, 0xf
},
};