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https://github.com/holub/mame
synced 2025-04-22 16:31:49 +03:00
i8275: handle invisible field attributes and "end of row - stop dma" special code better; honor Video Enable bit.
Fixes MT05764. No visual change on mikromik, tim100, zorba, and radio86 clones.
This commit is contained in:
Sergey Svishchev
Vas Crabb
parent
e0ac072a29
commit
f652d21e16
@ -11,6 +11,9 @@
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TODO:
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- double spaced rows
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- blanking of top and bottom rows when underline MSB is set
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- end of row/screen - stop dma
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- preset counters
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*/
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@ -106,6 +109,8 @@ i8275_device::i8275_device(const machine_config &mconfig, const char *tag, devic
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m_param_idx(0),
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m_param_end(0),
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m_buffer_idx(0),
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m_fifo_idx(0),
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m_dma_idx(0),
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m_fifo_next(false),
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m_buffer_dma(0),
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m_lpen(0),
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@ -156,6 +161,7 @@ void i8275_device::device_start()
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save_item(NAME(m_buffer[1]));
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save_item(NAME(m_buffer_idx));
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save_item(NAME(m_fifo_idx));
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save_item(NAME(m_dma_idx));
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save_item(NAME(m_fifo_next));
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save_item(NAME(m_buffer_dma));
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save_item(NAME(m_lpen));
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@ -215,8 +221,6 @@ void i8275_device::device_timer(emu_timer &timer, device_timer_id id, int param,
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break;
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case TIMER_SCANLINE:
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if (!(m_status & ST_VE)) break;
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//LOG("I8275 y %u x %u HRTC 0\n", y, x);
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m_write_hrtc(0);
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@ -226,11 +230,11 @@ void i8275_device::device_timer(emu_timer &timer, device_timer_id id, int param,
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m_write_vrtc(0);
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}
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if (m_scanline <= (m_vrtc_scanline - SCANLINES_PER_ROW))
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if ((m_status & ST_VE) && m_scanline <= (m_vrtc_scanline - SCANLINES_PER_ROW))
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{
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if (lc == 0)
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{
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if (m_buffer_idx < CHARACTERS_PER_ROW)
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if (m_dma_idx < CHARACTERS_PER_ROW)
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{
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m_status |= ST_DU;
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m_du = true;
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@ -246,6 +250,7 @@ void i8275_device::device_timer(emu_timer &timer, device_timer_id id, int param,
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m_buffer_dma = !m_buffer_dma;
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m_buffer_idx = 0;
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m_fifo_idx = 0;
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m_dma_idx = 0;
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if ((m_scanline < (m_vrtc_scanline - SCANLINES_PER_ROW)))
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{
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@ -271,37 +276,41 @@ void i8275_device::device_timer(emu_timer &timer, device_timer_id id, int param,
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//LOG("I8275 y %u x %u VRTC 1\n", y, x);
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m_write_vrtc(1);
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// reset field attributes
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m_hlgt = 0;
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m_vsp = 0;
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m_gpa = 0;
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m_rvv = 0,
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m_lten = 0;
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if (m_status & ST_VE)
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{
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// reset field attributes
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m_hlgt = 0;
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m_vsp = 0;
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m_gpa = 0;
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m_rvv = 0;
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m_lten = 0;
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m_du = false;
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m_dma_stop = false;
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m_end_of_screen = false;
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m_du = false;
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m_dma_stop = false;
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m_end_of_screen = false;
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m_cursor_blink++;
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m_cursor_blink &= 0x1f;
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m_cursor_blink++;
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m_cursor_blink &= 0x1f;
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m_char_blink++;
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m_char_blink &= 0x3f;
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m_stored_attr = 0;
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m_char_blink++;
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m_char_blink &= 0x3f;
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m_stored_attr = 0;
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}
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}
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if (m_scanline == m_vrtc_drq_scanline)
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if ((m_status & ST_VE) && m_scanline == m_vrtc_drq_scanline)
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{
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// swap line buffers
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m_buffer_dma = !m_buffer_dma;
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m_buffer_idx = 0;
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m_fifo_idx = 0;
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m_dma_idx = 0;
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// start DMA burst
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m_drq_on_timer->adjust(clocks_to_attotime(DMA_BURST_SPACE));
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}
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if (m_scanline < m_vrtc_scanline)
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if ((m_status & ST_VE) && m_scanline < m_vrtc_scanline)
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{
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int line_counter = OFFSET_LINE_COUNTER ? ((lc - 1) % SCANLINES_PER_ROW) : lc;
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bool end_of_row = false;
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@ -493,24 +502,41 @@ WRITE8_MEMBER( i8275_device::write )
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switch (data >> 5)
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{
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/*
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* DMA requests stop;
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* IE is reset, interrupts are disabled;
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* VE is reset, VSP output is used to blank the screen;
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* HRTC and VRTC continue to run;
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* HRTC and VRTC timing are random on power-up.
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*/
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case CMD_RESET:
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LOG("I8275 Reset\n");
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m_status &= ~ST_IE;
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m_status &= ~(ST_IE | ST_VE);
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LOG("I8275 IRQ 0\n");
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m_write_irq(CLEAR_LINE);
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m_write_drq(0);
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m_drq_on_timer->adjust(attotime::zero);
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m_param_idx = REG_SCN1;
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m_param_end = REG_SCN4;
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break;
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/*
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* IE is set, interrupts are enabled;
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* VE is set, video is enabled;
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* DMA requests begin.
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*/
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case CMD_START_DISPLAY:
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m_param[REG_DMA] = data;
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LOG("I8275 Start Display %u %u\n", DMA_BURST_COUNT, DMA_BURST_SPACE);
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m_status |= (ST_IE | ST_VE);
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break;
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/*
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* interrupts remain enabled;
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* HRTC and VRTC continue to run.
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*/
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case CMD_STOP_DISPLAY:
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LOG("I8275 Stop Display\n");
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m_status &= ~ST_VE;
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@ -540,7 +566,6 @@ WRITE8_MEMBER( i8275_device::write )
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case CMD_PRESET_COUNTERS:
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LOG("I8275 Preset Counters\n");
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m_scanline = 0;
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break;
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}
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}
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@ -566,7 +591,7 @@ WRITE8_MEMBER( i8275_device::write )
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WRITE8_MEMBER( i8275_device::dack_w )
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{
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//LOG("I8275 y %u x %u DACK %04x:%02x %u\n", screen().vpos(), screen().hpos(), offset, data, m_buffer_idx);
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//LOG("I8275 y %u x %u DACK %04x:%02x %u (%u)\n", screen().vpos(), screen().hpos(), offset, data, m_buffer_idx, m_dma_idx);
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m_write_drq(0);
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@ -584,41 +609,43 @@ WRITE8_MEMBER( i8275_device::dack_w )
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}
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else
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{
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if (m_buffer_idx < ARRAY_LENGTH(m_buffer[m_buffer_dma]))
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if (m_dma_idx < ARRAY_LENGTH(m_buffer[m_buffer_dma]))
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m_buffer[m_buffer_dma][m_buffer_idx++] = data;
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if (!VISIBLE_FIELD_ATTRIBUTE && ((data & 0xc0) == 0x80))
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{
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m_fifo_next = true;
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}
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}
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switch (data)
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m_dma_idx++;
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switch (data)
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{
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case SCC_END_OF_ROW_DMA:
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// stop DMA
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// TODO should read one more character if DMA burst not completed
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m_drq_on_timer->adjust(screen().time_until_pos(screen().vpos() + 1, 0));
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break;
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case SCC_END_OF_SCREEN_DMA:
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m_dma_stop = true;
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// TODO should read one more character if DMA burst not completed
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break;
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default:
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if (m_dma_idx == CHARACTERS_PER_ROW)
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{
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case SCC_END_OF_ROW_DMA:
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// stop DMA
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// TODO should read one more character if DMA burst not completed
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break;
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case SCC_END_OF_SCREEN_DMA:
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m_dma_stop = true;
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// TODO should read one more character if DMA burst not completed
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break;
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default:
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if (m_buffer_idx == CHARACTERS_PER_ROW)
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{
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// stop DMA
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}
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else if (!(m_buffer_idx % DMA_BURST_COUNT))
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{
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m_drq_on_timer->adjust(clocks_to_attotime(DMA_BURST_SPACE));
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}
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else
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{
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m_drq_on_timer->adjust(attotime::zero);
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}
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}
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else if (!(m_dma_idx % DMA_BURST_COUNT))
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{
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m_drq_on_timer->adjust(clocks_to_attotime(DMA_BURST_SPACE));
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}
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else
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{
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m_drq_on_timer->adjust(attotime::zero);
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}
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}
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}
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@ -688,6 +715,7 @@ void i8275_device::recompute_parameters()
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LOG("irq_y %u vrtc_y %u drq_y %u\n", m_irq_scanline, m_vrtc_scanline, m_vrtc_drq_scanline);
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m_scanline_timer->adjust(screen().time_until_pos(0, 0), 0, screen().scan_period());
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m_scanline = 0;
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if (DOUBLE_SPACED_ROWS) fatalerror("Double spaced rows not supported!");
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}
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@ -197,6 +197,7 @@ protected:
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uint8_t m_fifo[2][16];
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int m_buffer_idx;
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int m_fifo_idx;
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int m_dma_idx;
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bool m_fifo_next;
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int m_buffer_dma;
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