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2K ROM: refactor

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This commit is contained in:
tomcw 2018-11-21 21:21:54 +00:00
parent af899fa90a
commit cbd41333c9
1 changed files with 3 additions and 10 deletions
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13
source/NTSC_CharSet.cpp
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@ -181,25 +181,18 @@ void userVideoRom2K(csbits_t csbits, const BYTE* pVideoRom)
{
for (int y=0; y<8; y++)
{
BYTE d=0;
BYTE n = pVideoRom[RA+y];
// UTAII:8-30 "Bit 7 of your EPROM fonts will control flashing in the lower 1024 bytes of the EPROM"
// UTAII:8-31 "If you leave O7 (EPROM Output7) reset in these patterns, the resulting characters will be inversions..."
if (!(n & 0x80) && RA < 1024)
n = n ^ 0x7f;
n &= 0x7f;
// UTAII:8-30 "TEXT ROM pattern is ... reversed"
for (BYTE j=0; j<7; j++)
{
if (n & 1)
d |= 1;
d <<= 1;
n >>= 1;
}
BYTE d = 0;
for (BYTE j=0; j<7; j++, n >>= 1) // Just bits [0..6]
d = (d << 1) | (n & 1);
d >>= 1; // Undo the last left shift
csbits[0][i][y] = d;
}
}