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-rw-r--r--src/devices/machine/7200fifo.c138
1 files changed, 138 insertions, 0 deletions
diff --git a/src/devices/machine/7200fifo.c b/src/devices/machine/7200fifo.c
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+++ b/src/devices/machine/7200fifo.c
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+// license:BSD-3-Clause
+// copyright-holders:hap
+/**********************************************************************
+
+ IDT7200 series 9-bit Asynchronous FIFO Emulation
+
+ TODO:
+ - retransmit (RT pin)
+ - cascaded width expansion mode (when needed)
+
+**********************************************************************/
+
+#include "machine/7200fifo.h"
+
+
+const device_type FIFO7200 = &device_creator<fifo7200_device>;
+
+//-------------------------------------------------
+// fifo7200_device - constructor
+//-------------------------------------------------
+
+fifo7200_device::fifo7200_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock)
+ : device_t(mconfig, FIFO7200, "IDT7200 FIFO", tag, owner, clock, "fifo7200", __FILE__),
+ m_ram_size(0),
+ m_ef_handler(*this),
+ m_ff_handler(*this),
+ m_hf_handler(*this)
+{
+}
+
+//-------------------------------------------------
+// device_start - device-specific startup
+//-------------------------------------------------
+
+void fifo7200_device::device_start()
+{
+ assert(m_ram_size > 1 && ~m_ram_size & 1);
+ m_buffer.resize(m_ram_size);
+
+ // resolve callbacks
+ m_ef_handler.resolve_safe();
+ m_ff_handler.resolve_safe();
+ m_hf_handler.resolve_safe();
+
+ // state save
+ save_item(NAME(m_buffer));
+ save_item(NAME(m_read_ptr));
+ save_item(NAME(m_write_ptr));
+ save_item(NAME(m_ef));
+ save_item(NAME(m_ff));
+ save_item(NAME(m_hf));
+}
+
+//-------------------------------------------------
+// device_reset - device-specific reset
+//-------------------------------------------------
+
+void fifo7200_device::device_reset()
+{
+ // master reset
+ m_buffer.clear();
+ m_read_ptr = 0;
+ m_write_ptr = 0;
+
+ m_ef = 1;
+ m_ff = 0;
+ m_hf = 0;
+
+ m_ef_handler(!m_ef);
+ m_ff_handler(!m_ff);
+ m_hf_handler(!m_hf);
+}
+
+
+
+void fifo7200_device::fifo_write(UINT16 data)
+{
+ if (m_ff)
+ {
+ logerror("IDT7200 %s fifo_write overflow!\n", tag());
+ return;
+ }
+
+ m_buffer[m_write_ptr] = data & 0x1ff;
+ m_write_ptr = (m_write_ptr + 1) % m_ram_size;
+
+ // update flags
+ if (m_ef)
+ {
+ m_ef = 0;
+ m_ef_handler(!m_ef);
+ }
+
+ else if (m_read_ptr == m_write_ptr)
+ {
+ m_ff = 1;
+ m_ff_handler(!m_ff);
+ }
+
+ else if (((m_read_ptr + 1 + m_ram_size / 2) % m_ram_size) == m_write_ptr)
+ {
+ m_hf = 1;
+ m_hf_handler(!m_hf);
+ }
+}
+
+UINT16 fifo7200_device::fifo_read()
+{
+ if (m_ef)
+ {
+ logerror("IDT7200 %s fifo_read underflow!\n", tag());
+ return 0x1ff;
+ }
+
+ UINT16 ret = m_buffer[m_read_ptr];
+ m_read_ptr = (m_read_ptr + 1) % m_ram_size;
+
+ // update flags
+ if (m_ff)
+ {
+ m_ff = 0;
+ m_ff_handler(!m_ff);
+ }
+
+ else if (m_read_ptr == m_write_ptr)
+ {
+ m_ef = 1;
+ m_ef_handler(!m_ef);
+ }
+
+ else if (((m_read_ptr + m_ram_size / 2) % m_ram_size) == m_write_ptr)
+ {
+ m_hf = 0;
+ m_hf_handler(!m_hf);
+ }
+
+ return ret;
+}