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dirom: Make robust to too big roms

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This commit is contained in:
Olivier Galibert 2016-08-16 16:13:07 +02:00
parent 049c4c39cd
commit 429360df92
1 changed files with 31 additions and 27 deletions
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58
src/emu/dirom.cpp
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@ -18,38 +18,42 @@ const address_space_config *device_rom_interface::memory_space_config(address_sp
void device_rom_interface::set_rom(const void *base, UINT32 size)
{
UINT32 mend = m_rom_config.addr_width() == 32 ? 0xffffffff : (1 << m_rom_config.addr_width()) - 1;
UINT32 rend = size-1;
if(rend == mend)
space().install_rom(0, mend, const_cast<void *>(base));
else {
// Round up to the nearest power-of-two-minus-one
UINT32 rmask = rend;
rmask |= rmask >> 1;
rmask |= rmask >> 2;
rmask |= rmask >> 4;
rmask |= rmask >> 8;
rmask |= rmask >> 16;
if(rmask != rend)
space().unmap_read(0, mend);
// Mirror over the high bits. mend and rmask are both
// powers-of-two-minus-one, so the xor works
space().install_rom(0, rend, mend ^ rmask, const_cast<void *>(base));
}
UINT32 mend = m_rom_config.addr_width() == 32 ? 0xffffffff : (1 << m_rom_config.addr_width()) - 1;
UINT32 rend = size-1;
if(rend > mend) {
device().logerror("Warning: The rom for device %s is %x bytes, while the chip addressing space is only %x bytes.\n", device().tag(), rend+1, mend+1);
rend = mend;
}
if(rend == mend)
space().install_rom(0, mend, const_cast<void *>(base));
else {
// Round up to the nearest power-of-two-minus-one
UINT32 rmask = rend;
rmask |= rmask >> 1;
rmask |= rmask >> 2;
rmask |= rmask >> 4;
rmask |= rmask >> 8;
rmask |= rmask >> 16;
if(rmask != rend)
space().unmap_read(0, mend);
// Mirror over the high bits. mend and rmask are both
// powers-of-two-minus-one, so the xor works
space().install_rom(0, rend, mend ^ rmask, const_cast<void *>(base));
}
}
void device_rom_interface::interface_pre_start()
{
m_rom_direct = &space().direct();
m_rom_direct = &space().direct();
if(!has_configured_map(0)) {
memory_region *reg = device().memregion(DEVICE_SELF);
if(reg)
set_rom(reg->base(), reg->bytes());
else {
UINT32 end = m_rom_config.addr_width() == 32 ? 0xffffffff : (1 << m_rom_config.addr_width()) - 1;
space().unmap_read(0, end);
if(!has_configured_map(0)) {
memory_region *reg = device().memregion(DEVICE_SELF);
if(reg)
set_rom(reg->base(), reg->bytes());
else {
UINT32 end = m_rom_config.addr_width() == 32 ? 0xffffffff : (1 << m_rom_config.addr_width()) - 1;
space().unmap_read(0, end);
}
}
}
}