diff options
Diffstat (limited to 'src/devices/cpu/alto2/a2dwt.cpp')
-rw-r--r-- | src/devices/cpu/alto2/a2dwt.cpp | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/src/devices/cpu/alto2/a2dwt.cpp b/src/devices/cpu/alto2/a2dwt.cpp new file mode 100644 index 00000000000..b5fd716617c --- /dev/null +++ b/src/devices/cpu/alto2/a2dwt.cpp @@ -0,0 +1,62 @@ +// license:BSD-3-Clause +// copyright-holders:Juergen Buchmueller +/***************************************************************************** + * + * Xerox AltoII display word task + * + *****************************************************************************/ +#include "alto2cpu.h" + +//! PROM a38 bit O1 is STOPWAKE' (stop DWT if bit is zero) +#define FIFO_STOPWAKE(a38) (0 == (a38 & disp_a38_STOPWAKE) ? true : false) + +/** + * @brief block the display word task + */ +void alto2_cpu_device::f1_early_dwt_block() +{ + m_dsp.dwt_blocks = true; + + /* clear the wakeup for the display word task */ + m_task_wakeup &= ~(1 << m_task); + LOG((this,LOG_DWT,2," BLOCK %s\n", task_name(m_task))); + + /* wakeup the display horizontal task, if it didn't block itself */ + if (!m_dsp.dht_blocks) + m_task_wakeup |= 1 << task_dht; +} + +/** + * @brief load the display data register + */ +void alto2_cpu_device::f2_late_dwt_load_ddr() +{ + LOG((this,LOG_DWT,2," DDR<- BUS (%#o)\n", m_bus)); + m_dsp.fifo[m_dsp.wa] = m_bus; + m_dsp.wa = (m_dsp.wa + 1) % ALTO2_DISPLAY_FIFO; + UINT8 a38 = m_disp_a38[m_dsp.ra * 16 + m_dsp.wa]; + if (FIFO_STOPWAKE(a38)) + m_task_wakeup &= ~(1 << task_dwt); + LOG((this,LOG_DWT,2, " DWT push %04x into FIFO[%02o]%s\n", + m_bus, (m_dsp.wa - 1) & (ALTO2_DISPLAY_FIFO - 1), + FIFO_STOPWAKE(a38) ? " STOPWAKE" : "")); +} + +void alto2_cpu_device::init_dwt(int task) +{ + set_f1(task, f1_block, &alto2_cpu_device::f1_early_dwt_block, 0); + set_f2(task, f2_dwt_load_ddr, 0, &alto2_cpu_device::f2_late_dwt_load_ddr); +} + +void alto2_cpu_device::exit_dwt() +{ + // nothing to do yet +} + +void alto2_cpu_device::reset_dwt() +{ + m_dsp.dwt_blocks = false; + memset(m_dsp.fifo, 0, sizeof(m_dsp.fifo)); + m_dsp.wa = 0; + m_dsp.ra = 0; +} |