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-rw-r--r--src/devices/machine/acorn_lc.cpp152
1 files changed, 152 insertions, 0 deletions
diff --git a/src/devices/machine/acorn_lc.cpp b/src/devices/machine/acorn_lc.cpp
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+++ b/src/devices/machine/acorn_lc.cpp
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+// license:BSD-3-Clause
+// copyright-holders:Nigel Barnes
+/*********************************************************************
+
+ Acorn LC ASIC (for Acorn A4)
+
+ No public documentation exists, this is mostly based on the A4 TRM.
+
+*********************************************************************/
+
+#include "emu.h"
+#include "acorn_lc.h"
+#include "screen.h"
+
+
+DEFINE_DEVICE_TYPE(ACORN_LC, acorn_lc_device, "acorn_lc", "Acorn LC ASIC")
+
+//**************************************************************************
+// LIVE DEVICE
+//**************************************************************************
+
+//-------------------------------------------------
+// acorn_lc_device - constructor
+//-------------------------------------------------
+
+acorn_lc_device::acorn_lc_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
+ : device_t(mconfig, ACORN_LC, tag, owner, clock)
+ //, device_memory_interface(mconfig, *this)
+ //, device_palette_interface(mconfig, *this)
+ //, device_video_interface(mconfig, *this)
+ , m_vdsr(0)
+ , m_vdlr(0)
+ , m_hdsr(0)
+ , m_hdlr(0)
+ , m_licr(0)
+{
+}
+
+//-------------------------------------------------
+// device_start - device-specific startup
+//-------------------------------------------------
+
+void acorn_lc_device::device_start()
+{
+ // state saving
+ save_item(NAME(m_vdsr));
+ save_item(NAME(m_vdlr));
+ save_item(NAME(m_hdsr));
+ save_item(NAME(m_hdlr));
+ save_item(NAME(m_licr));
+}
+
+
+//**************************************************************************
+// READ/WRITE HANDLERS
+//**************************************************************************
+
+u8 acorn_lc_device::read(offs_t offset)
+{
+ u8 data = 0xff;
+
+ switch (offset & 0x0f)
+ {
+ case LC_LICR_L:
+ data = m_licr & 0x0f;
+ break;
+ case LC_LICR_M:
+ data = (m_licr >> 4) & 0x0f;
+ break;
+ case LC_LICR_H:
+ data = (m_licr >> 8) & 0x0f;
+ break;
+
+ case LC_RESET:
+ data = 0x04;
+ break;
+ }
+ logerror("lc_r: % 04x % 02x\n", offset, data);
+ return data;
+}
+
+void acorn_lc_device::write(offs_t offset, u8 data)
+{
+ logerror("lc_w: % 04x % 02x\n", offset, data);
+ switch (offset & 0x0f)
+ {
+ case LC_VDSR_L:
+ m_vdsr = (m_vdsr & 0x0ff0) | (data & 0x0f);
+ break;
+ case LC_VDSR_M:
+ m_vdsr = (m_vdsr & 0x0f0f) | ((data & 0x0f) << 4);
+ break;
+ case LC_VDSR_H:
+ m_vdsr = (m_vdsr & 0x00ff) | ((data & 0x0f) << 8);
+ break;
+
+ case LC_VDLR_L:
+ m_vdlr = (m_vdlr & 0x0ff0) | (data & 0x0f);
+ break;
+ case LC_VDLR_M:
+ m_vdlr = (m_vdlr & 0x0f0f) | ((data & 0x0f) << 4);
+ break;
+ case LC_VDLR_H:
+ m_vdlr = (m_vdlr & 0x00ff) | ((data & 0x0f) << 8);
+ break;
+
+ case LC_HDSR_L:
+ m_hdsr = (m_hdsr & 0x0ff0) | (data & 0x0f);
+ break;
+ case LC_HDSR_M:
+ m_hdsr = (m_hdsr & 0x0f0f) | ((data & 0x0f) << 4);
+ break;
+ case LC_HDSR_H:
+ m_hdsr = (m_hdsr & 0x00ff) | ((data & 0x0f) << 8);
+ break;
+
+ case LC_HDLR_L:
+ m_hdlr = (m_hdlr & 0x0ff0) | (data & 0x0f);
+ break;
+ case LC_HDLR_M:
+ m_hdlr = (m_hdlr & 0x0f0f) | ((data & 0x0f) << 4);
+ break;
+ case LC_HDLR_H:
+ m_hdlr = (m_hdlr & 0x00ff) | ((data & 0x0f) << 8);
+ break;
+
+ case LC_LICR_L:
+ m_licr = (m_licr & 0x0ff0) | (data & 0x0f);
+ break;
+ case LC_LICR_M:
+ m_licr = (m_licr & 0x0f0f) | ((data & 0x0f) << 4);
+ switch (m_licr & LICR_CLOCK_MASK)
+ {
+ case LICR_CLOCK_CRYS:
+ //m_vidc->set_unscaled_clock(24_MHz_XTAL);
+ break;
+ case LICR_CLOCK_CRYS2:
+ //m_vidc->set_unscaled_clock(24_MHz_XTAL / 2);
+ break;
+ case LICR_CLOCK_IOEB:
+ default:
+ //m_vidc->set_unscaled_cloc(ioeb_clock_select);
+ break;
+ }
+ break;
+ case LC_LICR_H:
+ m_licr = (m_licr & 0x00ff) | ((data & 0x0f) << 8);
+ break;
+ }
+ //if (offset & 0x40)
+ //pal[(offset >> 2) & 0xf] = lc_palette[data & 0xf];
+}