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(mess) pc9801: adjust mask if necessary (nw)

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This commit is contained in:
cracyc 2014-12-14 18:12:33 -06:00
parent b138ab152f
commit 1faec0116c
1 changed files with 19 additions and 7 deletions
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26
src/mess/drivers/pc9801.c
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@ -1351,13 +1351,13 @@ inline UINT16 pc9801_state::egc_do_partial_op(int plane, UINT16 src, UINT16 pat,
{
src = src_tmp << (dst_off - src_off);
src |= m_egc.leftover[plane];
m_egc.leftover[plane] = src_tmp >> (15 - (dst_off - src_off));
m_egc.leftover[plane] = src_tmp >> (16 - (dst_off - src_off));
}
else
{
src = src_tmp >> (src_off - dst_off);
src |= m_egc.leftover[plane];
m_egc.leftover[plane] = src_tmp << (15 - (src_off - dst_off));
m_egc.leftover[plane] = src_tmp << (16 - (src_off - dst_off));
}
for(int i = 7; i >= 0; i--)
@ -1380,16 +1380,28 @@ void pc9801_state::egc_blit_w(UINT32 offset, UINT16 data, UINT16 mem_mask)
if((((m_egc.regs[2] >> 11) & 3) == 1) || ((((m_egc.regs[2] >> 11) & 3) == 2) && !BIT(m_egc.regs[2], 10)))
{
// mask off the bits past the end of the blit
if(m_egc.count < 16)
mask &= dir ? ((1 << m_egc.count) - 1) : ~((1 << (16 - m_egc.count)) - 1);
UINT16 end_mask = 0xffff, start_mask = 0xffff;
// mask off the bits before the start
if(m_egc.first)
{
m_egc.leftover[0] = m_egc.leftover[1] = m_egc.leftover[2] = m_egc.leftover[3] = 0;
mask &= dir ? ~((1 << dst_off) - 1) : ((1 << (16 - dst_off)) - 1);
start_mask = dir ? ~((1 << dst_off) - 1) : ((1 << (15 - dst_off)) - 1);
}
// mask off the bits past the end of the blit
if(m_egc.count < 16)
{
end_mask = dir ? ((1 << m_egc.count) - 1) : ~((1 << (16 - m_egc.count)) - 1);
// if the blit is less than 16 bits, adjust the masks
if(start_mask != 0xffff)
{
if(dir)
end_mask <<= dst_off;
else
end_mask >>= (15 - dst_off);
}
}
mask &= end_mask & start_mask;
}
for(int i = 0; i < 4; i++)