+++ /dev/null
-\r
-// This file is part of the PicoDrive Megadrive Emulator\r
-\r
-// Copyright (c) 2011 FinalDave (emudave (at) gmail.com)\r
-\r
-// This code is licensed under the GNU General Public License version 2.0 and the MAME License.\r
-// You can choose the license that has the most advantages for you.\r
-\r
-// SVN repository can be found at http://code.google.com/p/cyclone68000/\r
-\r
-#include "PicoInt.h"\r
-\r
-static inline void AutoIncrement()\r
-{\r
- Pico.video.addr=(unsigned short)(Pico.video.addr+Pico.video.reg[0xf]);\r
-}\r
-\r
-static void VideoWrite(unsigned int d)\r
-{\r
- unsigned int a=0;\r
- unsigned short sd=(unsigned short)d;\r
-\r
- a=Pico.video.addr;\r
- if (a&1) d=((d<<8)&0xff00)|(d>>8); // If address is odd, bytes are swapped\r
- a>>=1;\r
-\r
- switch (Pico.video.type)\r
- {\r
- case 1: Pico.vram [a&0x7fff]=sd; break;\r
- case 3: Pico.cram [a&0x003f]=sd; Pico.m.dirtyPal=1; break;\r
- case 5: Pico.vsram[a&0x003f]=sd; break;\r
- }\r
- \r
- AutoIncrement();\r
-}\r
-\r
-static unsigned int VideoRead()\r
-{\r
- unsigned int a=0,d=0;\r
-\r
- a=Pico.video.addr; a>>=1;\r
-\r
- switch (Pico.video.type)\r
- {\r
- case 0: d=Pico.vram [a&0x7fff]; break;\r
- case 8: d=Pico.cram [a&0x003f]; break;\r
- case 4: d=Pico.vsram[a&0x003f]; break;\r
- }\r
- \r
- AutoIncrement();\r
- return d;\r
-}\r
-\r
-static int GetDmaSource()\r
-{\r
- struct PicoVideo *pvid=&Pico.video;\r
- int source=0;\r
- source =pvid->reg[0x15]<<1;\r
- source|=pvid->reg[0x16]<<9;\r
- source|=pvid->reg[0x17]<<17;\r
- return source;\r
-}\r
-\r
-static int GetDmaLength()\r
-{\r
- struct PicoVideo *pvid=&Pico.video;\r
- int len=0;\r
- // 16-bit words to transfer:\r
- len =pvid->reg[0x13];\r
- len|=pvid->reg[0x14]<<8;\r
- return len;\r
-}\r
-\r
-static void DmaSlow(int source,int len)\r
-{\r
- int i=0,max=0;\r
-\r
- if (source>=0x800000 && source<0xe00000) return; // Invalid source address\r
-\r
- /// Clip Cram DMA size (Todds Adventures in Slime World):\r
- if (Pico.video.type==3) { max=0x80-Pico.video.addr; if (len>max) len=max; }\r
-\r
- for (i=0;i<len;i++)\r
- {\r
- VideoWrite(PicoRead16(source));\r
- source+=2;\r
- }\r
-}\r
-\r
-static void DmaCopy(int source,int len)\r
-{\r
- int i=0;\r
-\r
- len>>=1; // Length specifies number of bytes\r
-\r
- for (i=0;i<len;i++)\r
- {\r
- VideoWrite(Pico.vram[source&0x7fff]);\r
- source+=2;\r
- }\r
-}\r
-\r
-static void DmaFill(int data)\r
-{\r
- int len=0,i=0;\r
- \r
- len=GetDmaLength();\r
-\r
- for (i=0;i<len+1;i++) VideoWrite(data);\r
-}\r
-\r
-static void CommandDma()\r
-{\r
- struct PicoVideo *pvid=&Pico.video;\r
- int len=0,method=0,source=0;\r
-\r
- if ((pvid->reg[1]&0x10)==0) return; // DMA not enabled\r
-\r
- len=GetDmaLength();\r
-\r
- method=pvid->reg[0x17]>>6;\r
- source=GetDmaSource();\r
- if (method< 2) DmaSlow(source,len); // 68000 to VDP\r
- if (method==3) DmaCopy(source,len); // VRAM Copy\r
-}\r
-\r
-static void CommandChange()\r
-{\r
- struct PicoVideo *pvid=&Pico.video;\r
- unsigned int cmd=0,addr=0;\r
-\r
- cmd=pvid->command;\r
-\r
- // Get type of transfer 0xc0000030 (v/c/vsram read/write)\r
- pvid->type=(unsigned char)(((cmd>>2)&0xc)|(cmd>>30));\r
-\r
- // Get address 0x3fff0003\r
- addr =(cmd>>16)&0x3fff;\r
- addr|=(cmd<<14)&0xc000;\r
- pvid->addr=(unsigned short)addr;\r
-\r
- // Check for dma:\r
- if (cmd&0x80) CommandDma();\r
-}\r
-\r
-void PicoVideoWrite(unsigned int a,unsigned int d)\r
-{\r
- struct PicoVideo *pvid=&Pico.video;\r
-\r
- a&=0x1c;\r
- d=(unsigned short)d;\r
-\r
- if (a==0x00) // Data port 0 or 2\r
- { \r
- if (pvid->pending) CommandChange();\r
- pvid->pending=0;\r
-\r
- // If a DMA fill has been set up, do it\r
- if ((pvid->command&0x80) && (pvid->reg[1]&0x10) && (pvid->reg[0x17]>>6)==2)\r
- {\r
- DmaFill(d);\r
- }\r
- else\r
- {\r
- VideoWrite(d);\r
- }\r
- return;\r
- }\r
-\r
- if (a==0x04) // Command port 4 or 6\r
- {\r
- if (pvid->pending)\r
- {\r
- // Low word of command:\r
- pvid->command&=0xffff0000;\r
- pvid->command|=d;\r
- pvid->pending=0;\r
- CommandChange();\r
- return;\r
- }\r
-\r
- if ((d&0xc000)==0x8000)\r
- {\r
- // Register write:\r
- int num=(d>>8)&0x1f;\r
- pvid->reg[num]=(unsigned char)d;\r
- return;\r
- }\r
-\r
- // High word of command:\r
- pvid->command&=0x0000ffff;\r
- pvid->command|=d<<16;\r
- pvid->pending=1;\r
- }\r
-}\r
-\r
-unsigned int PicoVideoRead(unsigned int a)\r
-{\r
- unsigned int d=0;\r
- \r
- a&=0x1c;\r
-\r
- if (a==0x00) { d=VideoRead(); goto end; }\r
-\r
- if (a==0x04)\r
- {\r
- d=Pico.video.status;\r
-\r
- // Toggle fifo full empty:\r
- if (Pico.m.rotate&4) d|=0x3520; else d|=0x3620;\r
- if (Pico.m.rotate&2) d|=0x0004; // Toggle in/out of H-Blank\r
- Pico.m.rotate++;\r
-\r
- if (Pico.m.pal) d|=1; // PAL screen\r
-\r
- goto end;\r
- }\r
-\r
- if ((a&0x1c)==0x08)\r
- {\r
- if (Pico.m.scanline>-64) d=Pico.m.scanline; // HV-Counter\r
- else d=Pico.m.rotate++; // Fudge\r
-\r
- d&=0xff; d<<=8;\r
- goto end;\r
- }\r
-\r
-end:\r
-\r
- return d;\r
-}\r
notaz.gp2x.de / cyclone68000.git / blobdiff