summaryrefslogtreecommitdiffstats
path: root/src/mess/video/bbc.c
diff options
context:
space:
mode:
authorGravatarGravatar Miodrag Milanovic <mmicko@gmail.com>2015-09-30 17:21:14 +0200
committerGravatarGravatar Miodrag Milanovic <mmicko@gmail.com>2015-09-30 17:21:14 +0200
commit1fc48ce120a376c288daeeed98daccecf1b60d7b (patch)
tree72cefcede17f3a27fa8256b43bfac9756db82312 /src/mess/video/bbc.c
parent87a576c55501bd7125b51ca786a010229669df0e (diff)
downloadmame-1fc48ce120a376c288daeeed98daccecf1b60d7b.tar.xz
mame-1fc48ce120a376c288daeeed98daccecf1b60d7b.zip
move mess into mame (nw)
Diffstat (limited to 'src/mess/video/bbc.c')
-rw-r--r--src/mess/video/bbc.c306
1 files changed, 0 insertions, 306 deletions
diff --git a/src/mess/video/bbc.c b/src/mess/video/bbc.c
deleted file mode 100644
index 5e059647705..00000000000
--- a/src/mess/video/bbc.c
+++ /dev/null
@@ -1,306 +0,0 @@
-// license:BSD-3-Clause
-// copyright-holders:Gordon Jefferyes, Nigel Barnes
-/******************************************************************************
- BBC Model B
-
- MESS Driver By:
-
- Gordon Jefferyes
- mess_bbc@romvault.com
-
- This is the first go around at converting the BBC code over to using
- mames built in mc6845, there are a number of features now incorrect
- or missing in this build:
-
- BBC split modes no longer work (Like is used in Elite.)
-
-******************************************************************************/
-
-#include "emu.h"
-#include "includes/bbc.h"
-#include "video/saa5050.h"
-#include "video/mc6845.h"
-
-/************************************************************************
- * C0 and C1 along with MA12 output from the 6845 drive 4 NAND gates in ICs 27,36 and 40
- * the outputs from these NAND gates (B1 to B4) along with MA8 to MA11 from the 6845 (A1 to B4) are added together
- * in IC39 74LS283 4 bit adder to form (S1 to S4) the logic is used to loop the screen memory for hardware scrolling.
- * when MA13 from the 6845 is low the latches IC8 and IC9 are enabled
- * they control the memory addressing for the Hi-Res modes.
- * when MA13 from the 6845 is high the latches IC10 and IC11 are enabled
- * they control the memory addressing for the Teletext mode.
- * IC 8 or IC10 drives the row select in the memory (the lower 7 bits in the memory address) and
- * IC 9 or IC11 drives the column select in the memory (the next 7 bits in the memory address) this
- * gives control of the bottom 14 bits of the memory, in a 32K model B 15 bits are needed to access
- * all the RAM, so S4 for the adder drives the CAS0 and CAS1 to access the top bit, in a 16K model A
- * the output of S4 is linked out to a 0v supply by link S25 to just access the 16K memory area.
- ************************************************************************/
-
-unsigned int bbc_state::calculate_video_address(int ma,int ra)
-{
- // ma = output from IC2 6845 MA address
-
- int c0=m_b4_video0; // output from IC32 74LS259 bits 4 and 5
- int c1=m_b5_video1;
-
- /* the 4 bit input port b on IC39 are produced by 4 NAND gates.
- these NAND gates take their
- inputs from c0 and c1 (from IC32) and ma12 (from the 6845) */
-
- /* get bit m12 from the 6845 */
- int ma12=(ma>>12)&1;
-
- // 4 bit input B on IC39 74LS283 (4 bit adder)
- /* 3 input NAND part of IC 36 */
- int b1=(~(c1 & c0 & ma12)) & 1;
- /* 2 input NAND part of IC40 (b3 is calculated before b2 and b4 because b3 feed back into b2 and b4) */
- int b3=(~(c0 & ma12)) & 1;
- /* 3 input NAND part of IC 36 */
- int b2=(~(c1 & b3 & ma12)) & 1;
- /* 2 input NAND part of IC 27 */
- int b4=(~(b3 & ma12)) & 1;
-
- /* inputs port b to IC39 are taken from the NAND gates b1 to b4 */
- int b=(b1<<0)|(b2<<1)|(b3<<2)|(b4<<3);
-
- /* inputs port a to IC39 are MA8 to MA11 from the 6845 */
- int a=(ma>>8)&0xf;
-
- /* IC39 performs the 4 bit add with the carry input set high */
- int s=(a+b+1)&0xf;
-
- /* if MA13 (TTXVDU) is low then IC8 and IC9 are used to calculate
- the memory location required for the hi res video.
- if MA13 is hight then IC10 and IC11 are used to calculate the memory location for the teletext chip*/
- unsigned int m;
- if ((ma>>13)&1)
- {
- // IC 10 and IC 11
- m=((ma&0x3ff)|0x3c00)|((s&0x8)<<11);
- } else {
- // IC 8 and IC 9
- m=((ma&0xff)<<3)|(s<<11)|(ra&0x7);
- }
- if (m_memorySize==16)
- return m & 0x3fff;
-
- return m;
-}
-
-/************************************************************************
- * VideoULA
- ************************************************************************/
-
-static const int pixels_per_byte_set[8]={ 2,4,8,16,1,2,4,8 };
-
-static const int width_of_cursor_set[8]={ 0,0,1,2,1,0,2,4 };
-
-/* this is a quick lookup array that puts bits 0,2,4,6 into bits 0,1,2,3
- this is used by the palette lookup in the video ULA */
-void bbc_state::set_pixel_lookup()
-{
- for (int i=0; i<256; i++)
- {
- m_pixel_bits[i] = (((i>>7)&1)<<3) | (((i>>5)&1)<<2) | (((i>>3)&1)<<1) | (((i>>1)&1)<<0);
- }
-}
-
-
-WRITE8_MEMBER(bbc_state::bbc_videoULA_w)
-{
- // Make sure vpos is never <0 2008-10-11 PHS.
- int vpos=machine().first_screen()->vpos();
- if(vpos==0)
- machine().first_screen()->update_partial(vpos);
- else
- machine().first_screen()->update_partial(vpos -1 );
-
- logerror("setting videoULA %.4x to:%.4x at :%d \n",data,offset,machine().first_screen()->vpos() );
-
-
- switch (offset&0x01)
- {
- // Set the control register in the Video ULA
- case 0:
- {
- m_videoULA_Reg=data;
- m_videoULA_master_cursor_size= (m_videoULA_Reg>>7)&0x01;
- m_videoULA_width_of_cursor= (m_videoULA_Reg>>5)&0x03;
- m_videoULA_6845_clock_rate= (m_videoULA_Reg>>4)&0x01;
- m_videoULA_characters_per_line= (m_videoULA_Reg>>2)&0x03;
- m_videoULA_teletext_normal_select=(m_videoULA_Reg>>1)&0x01;
- m_videoULA_flash_colour_select= m_videoULA_Reg &0x01;
-
- m_videoULA_pallet_lookup=m_videoULA_flash_colour_select?m_videoULA_pallet0:m_videoULA_pallet1;
-
- m_emulation_cursor_size=width_of_cursor_set[m_videoULA_width_of_cursor|(m_videoULA_master_cursor_size<<2)];
-
- // this is the number of BBC pixels held in each byte
- if (m_videoULA_teletext_normal_select)
- {
- m_pixels_per_byte=6;
- } else {
- m_pixels_per_byte=pixels_per_byte_set[m_videoULA_characters_per_line|(m_videoULA_6845_clock_rate<<2)];
- }
- m_mc6845->set_hpixels_per_column(m_pixels_per_byte);
- if (m_videoULA_6845_clock_rate)
- m_mc6845->set_clock(2000000);
- else
- m_mc6845->set_clock(1000000);
- }
- break;
- // Set a pallet register in the Video ULA
- case 1:
- int tpal=(data>>4)&0x0f;
- int tcol=data&0x0f;
- m_videoULA_pallet0[tpal]=tcol;
- m_videoULA_pallet1[tpal]=tcol<8?tcol:tcol^7;
- break;
- }
-}
-
-/************************************************************************
- * BBC circuits controlled by 6845 Outputs
- ************************************************************************/
-
-MC6845_UPDATE_ROW( bbc_state::crtc_update_row )
-{
- const rgb_t *palette = m_palette->palette()->entry_list_raw();
-
- if (m_videoULA_teletext_normal_select)
- {
- m_trom->lose_w(1);
- m_trom->lose_w(0);
-
- for(int x_pos=0; x_pos<x_count; x_pos++)
- {
- //Teletext Latch bits 0 to 5 go to bits 0 to 5 on the Teletext chip
- //Teletext Latch bit 6 is only passed onto bits 6 on the Teletext chip if DE is true
- //Teletext Latch bit 7 goes to LOSE on the Teletext chip
-
- if (((ma>>13)&1)==0)
- {
- m_Teletext_Latch=0;
- }
- else
- {
- m_Teletext_Latch=(m_BBC_Video_RAM[calculate_video_address(ma+x_pos,ra)]);
- }
-
- m_trom->write((m_Teletext_Latch&0x3f)|(m_Teletext_Latch&0x40));
-
- m_trom->f1_w(1);
- m_trom->f1_w(0);
-
- for(int pixelno=0;pixelno<6;pixelno++)
- {
- m_trom->tr6_w(1);
- m_trom->tr6_w(0);
-
- int col=m_trom->get_rgb() ^ ((x_pos==cursor_x) ? 7 : 0);
-
- int r = BIT(col, 0) * 0xff;
- int g = BIT(col, 1) * 0xff;
- int b = BIT(col, 2) * 0xff;
-
- rgb_t rgb = rgb_t(r, g, b);
-
- bitmap.pix32(y, (x_pos*m_pixels_per_byte)+pixelno) = rgb;
- }
- }
-
- if (ra == 18)
- {
- m_trom->lose_w(1);
- m_trom->lose_w(0);
- }
- }
- else
- {
- // this is IC38 and IC41 takes 6845 DisplayEnabled and 6845 RA3
- int DE= !(ra>=8);
-
- if (DE)
- {
- for(int x_pos=0; x_pos<x_count; x_pos++)
- {
- int vmem=calculate_video_address(ma+x_pos,ra);
- unsigned char i=m_BBC_Video_RAM[vmem];
-
- for(int pixelno=0;pixelno<m_pixels_per_byte;pixelno++)
- {
- int col=m_videoULA_pallet_lookup[m_pixel_bits[i]] ^ ((x_pos==cursor_x) ? 7 : 0);
- bitmap.pix32(y, (x_pos*m_pixels_per_byte)+pixelno)=palette[col];
- i=(i<<1)|1;
- }
- }
- }
- else
- {
- for(int x_pos=0; x_pos<x_count; x_pos++)
- {
- for(int pixelno=0;pixelno<m_pixels_per_byte;pixelno++)
- {
- bitmap.pix32(y, (x_pos*m_pixels_per_byte)+pixelno)=palette[7];
- }
- }
- }
- }
-}
-
-WRITE_LINE_MEMBER(bbc_state::bbc_vsync)
-{
- m_trom->dew_w(state);
-}
-
-
-/**** BBC B+ Shadow Ram change ****/
-
-void bbc_state::bbcbp_setvideoshadow(int vdusel)
-{
- if (vdusel)
- {
- m_BBC_Video_RAM= m_region_maincpu->base()+0x8000;
- } else {
- m_BBC_Video_RAM= m_region_maincpu->base();
- }
-}
-
-/************************************************************************
- * bbc_vh_start
- * Initialize the BBC video emulation
- ************************************************************************/
-
-void bbc_state::common_init(int memorySize)
-{
- m_emulation_cursor_size = 1;
-
- m_VideoULA_CR = 7;
- m_VideoULA_CR_counter = 0;
-
- set_pixel_lookup();
-
- m_BBC_Video_RAM = m_region_maincpu->base();
- m_memorySize=memorySize;
-
-}
-
-VIDEO_START_MEMBER(bbc_state,bbca)
-{
- common_init(m_ram->size()/1024);
-}
-
-VIDEO_START_MEMBER(bbc_state,bbcb)
-{
- common_init(32);
-}
-
-VIDEO_START_MEMBER(bbc_state,bbcbp)
-{
- common_init(32);
-}
-
-VIDEO_START_MEMBER(bbc_state,bbcm)
-{
- common_init(32);
-}