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Diffstat (limited to 'trunk/src/emu/machine/i8243.c')
-rw-r--r-- | trunk/src/emu/machine/i8243.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/trunk/src/emu/machine/i8243.c b/trunk/src/emu/machine/i8243.c new file mode 100644 index 00000000000..cb1650413d2 --- /dev/null +++ b/trunk/src/emu/machine/i8243.c @@ -0,0 +1,170 @@ +/*************************************************************************** + + i8243.c + + Intel 8243 Port Expander + + Copyright Aaron Giles + +***************************************************************************/ + +#include "emu.h" +#include "i8243.h" +#include "devhelpr.h" + +//************************************************************************** +// LIVE DEVICE +//************************************************************************** + +// device type definition +const device_type I8243 = &device_creator<i8243_device>; + +//------------------------------------------------- +// i8243_device - constructor +//------------------------------------------------- + +i8243_device::i8243_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) + : device_t(mconfig, I8243, "I8243", tag, owner, clock) +{ + +} + + +//------------------------------------------------- +// static_set_read_handler - configuration helper +// to set the read handler +//------------------------------------------------- + +void i8243_device::static_set_read_handler(device_t &device, read8_device_func callback) +{ + i8243_device &i8243 = downcast<i8243_device &>(device); + if(callback != NULL) + { + i8243.m_readhandler_cb.type = DEVCB_TYPE_DEVICE; + i8243.m_readhandler_cb.index = 0; + i8243.m_readhandler_cb.tag = ""; + i8243.m_readhandler_cb.readdevice = callback; + } + else + { + i8243.m_readhandler_cb.type = DEVCB_TYPE_NULL; + } +} + + +//------------------------------------------------- +// static_set_write_handler - configuration helper +// to set the write handler +//------------------------------------------------- + +void i8243_device::static_set_write_handler(device_t &device, write8_device_func callback) +{ + i8243_device &i8243 = downcast<i8243_device &>(device); + if(callback != NULL) + { + i8243.m_writehandler_cb.type = DEVCB_TYPE_DEVICE; + i8243.m_writehandler_cb.index = 0; + i8243.m_writehandler_cb.tag = ""; + i8243.m_writehandler_cb.writedevice = callback; + } + else + { + i8243.m_writehandler_cb.type = DEVCB_TYPE_NULL; + } +} + + +//------------------------------------------------- +// device_start - device-specific startup +//------------------------------------------------- + +void i8243_device::device_start() +{ + m_readhandler.resolve(m_readhandler_cb, *this); + m_writehandler.resolve(m_writehandler_cb, *this); +} + + +//------------------------------------------------- +// device_reset - device-specific reset +//------------------------------------------------- + +void i8243_device::device_reset() +{ + m_p2 = 0x0f; + m_p2out = 0x0f; + m_prog = 1; +} + + +/*------------------------------------------------- + i8243_p2_r - handle a read from port 2 +-------------------------------------------------*/ + +READ8_DEVICE_HANDLER_TRAMPOLINE(i8243, i8243_p2_r) +{ + return m_p2out; +} + + +/*------------------------------------------------- + i8243_p2_r - handle a write to port 2 +-------------------------------------------------*/ + +WRITE8_DEVICE_HANDLER_TRAMPOLINE(i8243, i8243_p2_w) +{ + m_p2 = data & 0x0f; +} + + +/*------------------------------------------------- + i8243_prog_w - handle a change in the PROG + line state +-------------------------------------------------*/ + +WRITE8_DEVICE_HANDLER_TRAMPOLINE(i8243, i8243_prog_w) +{ + /* only care about low bit */ + data &= 1; + + /* on high->low transition state, latch opcode/port */ + if(m_prog && !data) + { + m_opcode = m_p2; + + /* if this is a read opcode, copy result to p2out */ + if((m_opcode >> 2) == MCS48_EXPANDER_OP_READ) + { + if (m_readhandler.isnull()) + { + m_p[m_opcode & 3] = m_readhandler(m_opcode & 3); + } + m_p2out = m_p[m_opcode & 3] & 0x0f; + } + } + + /* on low->high transition state, act on opcode */ + else if(!m_prog && data) + { + switch(m_opcode >> 2) + { + case MCS48_EXPANDER_OP_WRITE: + m_p[m_opcode & 3] = m_p2 & 0x0f; + m_writehandler(m_opcode & 3, m_p[m_opcode & 3]); + break; + + case MCS48_EXPANDER_OP_OR: + m_p[m_opcode & 3] |= m_p2 & 0x0f; + m_writehandler(m_opcode & 3, m_p[m_opcode & 3]); + break; + + case MCS48_EXPANDER_OP_AND: + m_p[m_opcode & 3] &= m_p2 & 0x0f; + m_writehandler(m_opcode & 3, m_p[m_opcode & 3]); + break; + } + } + + /* remember the state */ + m_prog = data; +} |