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Apple II double lo-res: work around issue #10760 (#10761)

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This implements the same workaround for double lo-res that was already
used for double hi-res: shift the whole image right by one pixel (losing
the rightmost pixel) in monochrome mode so that the NTSC shader is
happy. This doesn't affect color mode.
This commit is contained in:
benrg 2023-01-03 16:40:11 -08:00 committed by GitHub
parent 42159f1b5a
commit b7fab7f35e
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 27 additions and 88 deletions
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115
src/mame/apple/apple2video.cpp
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@ -430,109 +430,43 @@ void a2_video_device::dlores_update(screen_device &screen, bitmap_ind16 &bitmap,
{
for (int row = startrow; row < stoprow; row += 8)
{
/* calculate address */
uint32_t const address = start_address + ((((row/8) & 0x07) << 7) | (((row/8) & 0x18) * 5));
uint8_t prev_code = (startcol == 0) ? 0 : m_ram_ptr[address + startcol - 1];
for (int col = 0; col < 40; col++)
{
uint8_t bits, abits;
/* calculate adderss */
uint32_t const address = start_address + ((((row/8) & 0x07) << 7) | (((row/8) & 0x18) * 5 + col));
/* perform the lookup */
uint8_t const code = m_ram_ptr[address];
uint8_t const auxcode = m_aux_ptr[address];
bits = (code >> 0) & 0x0F;
abits = (auxcode >> 0) & 0x0F;
uint8_t const code = m_ram_ptr[address + col];
uint8_t const auxcode = m_aux_ptr[address + col];
/* and now draw */
for (int y = 0; y < 4; y++)
for (int y = 0; y < 8; y++)
{
if (((row + y) >= beginrow) && ((row + y) <= endrow))
{
uint16_t *vram = &bitmap.pix(row + y, (col * 14));
if (col & 1)
unsigned const color1 = (auxcode >> (y & 4)) & 0x0F;
unsigned const color2 = (code >> (y & 4)) & 0x0F;
unsigned allbits = (((color1 * 0x111) >> ((col * 14) & 3)) & 0x007f)
+ (((color2 * 0x8880) >> ((col * 14) & 3)) & 0x3f80);
// Workaround for Github issue #10760: shift everything right by one pixel
// (losing the last pixel of each row) so that the NTSC shader sees what
// it expects. This should be removed when there is a better fix.
unsigned const prev_bit = (prev_code >> ((y & 4) + ((col * 14) & 3))) & 1;
allbits = allbits * 2 + prev_bit;
for (int x = 0; x < 14; x++)
{
*vram++ = abits & (1 << 2) ? fg : 0;
*vram++ = abits & (1 << 3) ? fg : 0;
*vram++ = abits & (1 << 0) ? fg : 0;
*vram++ = abits & (1 << 1) ? fg : 0;
*vram++ = abits & (1 << 2) ? fg : 0;
*vram++ = abits & (1 << 3) ? fg : 0;
*vram++ = abits & (1 << 0) ? fg : 0;
*vram++ = bits & (1 << 1) ? fg : 0;
*vram++ = bits & (1 << 2) ? fg : 0;
*vram++ = bits & (1 << 3) ? fg : 0;
*vram++ = bits & (1 << 0) ? fg : 0;
*vram++ = bits & (1 << 1) ? fg : 0;
*vram++ = bits & (1 << 2) ? fg : 0;
*vram++ = bits & (1 << 3) ? fg : 0;
}
else
{
*vram++ = abits & (1 << 0) ? fg : 0;
*vram++ = abits & (1 << 1) ? fg : 0;
*vram++ = abits & (1 << 2) ? fg : 0;
*vram++ = abits & (1 << 3) ? fg : 0;
*vram++ = abits & (1 << 0) ? fg : 0;
*vram++ = abits & (1 << 1) ? fg : 0;
*vram++ = abits & (1 << 2) ? fg : 0;
*vram++ = bits & (1 << 0) ? fg : 0;
*vram++ = bits & (1 << 1) ? fg : 0;
*vram++ = bits & (1 << 2) ? fg : 0;
*vram++ = bits & (1 << 3) ? fg : 0;
*vram++ = bits & (1 << 0) ? fg : 0;
*vram++ = bits & (1 << 1) ? fg : 0;
*vram++ = bits & (1 << 2) ? fg : 0;
*vram++ = allbits & (1 << x) ? fg : 0;
}
}
}
bits = (code >> 4) & 0x0F;
abits = (auxcode >> 4) & 0x0F;
for (int y = 4; y < 8; y++)
{
if (((row + y) >= beginrow) && ((row + y) <= endrow))
{
uint16_t *vram = &bitmap.pix(row + y, (col * 14));
if (col & 1)
{
*vram++ = abits & (1 << 2) ? fg : 0;
*vram++ = abits & (1 << 3) ? fg : 0;
*vram++ = abits & (1 << 0) ? fg : 0;
*vram++ = abits & (1 << 1) ? fg : 0;
*vram++ = abits & (1 << 2) ? fg : 0;
*vram++ = abits & (1 << 3) ? fg : 0;
*vram++ = abits & (1 << 0) ? fg : 0;
*vram++ = bits & (1 << 1) ? fg : 0;
*vram++ = bits & (1 << 2) ? fg : 0;
*vram++ = bits & (1 << 3) ? fg : 0;
*vram++ = bits & (1 << 0) ? fg : 0;
*vram++ = bits & (1 << 1) ? fg : 0;
*vram++ = bits & (1 << 2) ? fg : 0;
*vram++ = bits & (1 << 3) ? fg : 0;
}
else
{
*vram++ = abits & (1 << 0) ? fg : 0;
*vram++ = abits & (1 << 1) ? fg : 0;
*vram++ = abits & (1 << 2) ? fg : 0;
*vram++ = abits & (1 << 3) ? fg : 0;
*vram++ = abits & (1 << 0) ? fg : 0;
*vram++ = abits & (1 << 1) ? fg : 0;
*vram++ = abits & (1 << 2) ? fg : 0;
*vram++ = bits & (1 << 0) ? fg : 0;
*vram++ = bits & (1 << 1) ? fg : 0;
*vram++ = bits & (1 << 2) ? fg : 0;
*vram++ = bits & (1 << 3) ? fg : 0;
*vram++ = bits & (1 << 0) ? fg : 0;
*vram++ = bits & (1 << 1) ? fg : 0;
*vram++ = bits & (1 << 2) ? fg : 0;
}
}
}
prev_code = code;
}
}
}
@ -895,6 +829,9 @@ void a2_video_device::dhgr_update(screen_device &screen, bitmap_ind16 &bitmap, c
break;
case 1:
// Shifting by 6 instead of 7 here shifts the entire DHGR screen right one pixel, so the leftmost pixel is
// always black and the rightmost pixel is not shown. This is to work around a problem with the HLSL NTSC
// shader. See Github issues #6308 and #10759. This should be changed when there is a better solution.
w >>= 6;
for (int b = 0; b < 7; b++)
{
@ -905,6 +842,7 @@ void a2_video_device::dhgr_update(screen_device &screen, bitmap_ind16 &bitmap, c
break;
case 2:
// See case 1
w >>= 6;
for (int b = 0; b < 7; b++)
{
@ -915,6 +853,7 @@ void a2_video_device::dhgr_update(screen_device &screen, bitmap_ind16 &bitmap, c
break;
case 3:
// See case 1
w >>= 6;
for (int b = 0; b < 7; b++)
{