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Corrected fat low-res implementation.

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As per comment of awanderin that "the odd addresses don't get their pixels auto-shifted by the hardware as with normal lo-res".
This commit is contained in:
Thomas Harte 2018-09-09 10:06:21 -04:00
parent d70f5da94e
commit 8d79a1e381
1 changed files with 7 additions and 15 deletions
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22
Machines/AppleII/Video.cpp
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@ -246,21 +246,13 @@ void VideoBase::output_low_resolution(uint8_t *target, const uint8_t *const sour
void VideoBase::output_fat_low_resolution(uint8_t *target, const uint8_t *const source, size_t length, int column, int row) const {
const int row_shift = row&4;
for(size_t c = 0; c < length; ++c) {
// Low-resolution graphics mode shifts the colour code on a loop, but has to account for whether this
// 14-sample output window is starting at the beginning of a colour cycle or halfway through.
if((column + static_cast<int>(c))&1) {
target[0] = target[1] = target[8] = target[9] = (source[c] >> row_shift) & 4;
target[2] = target[3] = target[10] = target[11] = (source[c] >> row_shift) & 8;
target[4] = target[5] = target[12] = target[13] = (source[c] >> row_shift) & 1;
target[6] = target[7] = (source[c] >> row_shift) & 2;
graphics_carry_ = (source[c] >> row_shift) & 8;
} else {
target[0] = target[1] = target[8] = target[9] = (source[c] >> row_shift) & 1;
target[2] = target[3] = target[10] = target[11] = (source[c] >> row_shift) & 2;
target[4] = target[5] = target[12] = target[13] = (source[c] >> row_shift) & 4;
target[6] = target[7] = (source[c] >> row_shift) & 8;
graphics_carry_ = (source[c] >> row_shift) & 2;
}
// Fat low-resolution mode appears not to do anything to try to make odd and
// even columns compatible.
target[0] = target[1] = target[8] = target[9] = (source[c] >> row_shift) & 1;
target[2] = target[3] = target[10] = target[11] = (source[c] >> row_shift) & 2;
target[4] = target[5] = target[12] = target[13] = (source[c] >> row_shift) & 4;
target[6] = target[7] = (source[c] >> row_shift) & 8;
graphics_carry_ = (source[c] >> row_shift) & 4;
target += 14;
}
}