118 lines
4.8 KiB
C
118 lines
4.8 KiB
C
/*STG1702 true colour RAMDAC emulation*/
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#include "ibm.h"
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#include "mem.h"
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#include "video.h"
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#include "vid_svga.h"
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#include "vid_stg_ramdac.h"
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static int stg_state_read[2][8] = {{1,2,3,4,0,0,0,0}, {1,2,3,4,5,6,7,7}};
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static int stg_state_write[8] = {0,0,0,0,0,6,7,7};
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void stg_ramdac_out(uint16_t addr, uint8_t val, stg_ramdac_t *ramdac, svga_t *svga)
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{
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int didwrite;
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//if (CS!=0xC000) pclog("OUT RAMDAC %04X %02X %i %04X:%04X\n",addr,val,stg_ramdac.magic_count,CS,pc);
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switch (addr)
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{
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case 0x3c6:
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switch (ramdac->magic_count)
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{
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case 0: case 1: case 2: case 3:
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break;
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case 4:
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ramdac->command = val;
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/*pclog("Write RAMDAC command %02X\n",val);*/
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break;
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case 5:
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ramdac->index = (ramdac->index & 0xff00) | val;
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break;
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case 6:
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ramdac->index = (ramdac->index & 0xff) | (val << 8);
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break;
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case 7:
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pclog("Write RAMDAC reg %02X %02X\n", ramdac->index, val);
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if (ramdac->index < 0x100)
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ramdac->regs[ramdac->index] = val;
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ramdac->index++;
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break;
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}
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didwrite = (ramdac->magic_count >= 4);
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ramdac->magic_count = stg_state_write[ramdac->magic_count & 7];
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if (ramdac->command & 8)
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{
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switch (ramdac->regs[3])
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{
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case 0: case 5: case 7: svga->bpp = 8; break;
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case 1: case 2: case 8: svga->bpp = 15; break;
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case 3: case 6: svga->bpp = 16; break;
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case 4: case 9: svga->bpp = 24; break;
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default: svga->bpp = 8; break;
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}
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}
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else
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{
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switch (ramdac->command >> 5)
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{
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case 0: svga->bpp = 8; break;
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case 5: svga->bpp = 15; break;
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case 6: svga->bpp = 16; break;
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case 7: svga->bpp = 24; break;
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default: svga->bpp = 8; break;
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}
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}
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if (didwrite) return;
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break;
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case 0x3c7: case 0x3c8: case 0x3c9:
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ramdac->magic_count=0;
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break;
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}
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svga_out(addr, val, svga);
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}
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uint8_t stg_ramdac_in(uint16_t addr, stg_ramdac_t *ramdac, svga_t *svga)
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{
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uint8_t temp;
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//if (CS!=0xC000) pclog("IN RAMDAC %04X %04X:%04X\n",addr,CS,pc);
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switch (addr)
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{
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case 0x3c6:
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switch (ramdac->magic_count)
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{
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case 0: case 1: case 2: case 3:
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temp = 0xff;
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break;
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case 4:
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temp = ramdac->command;
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break;
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case 5:
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temp = ramdac->index & 0xff;
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break;
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case 6:
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temp = ramdac->index >> 8;
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break;
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case 7:
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// pclog("Read RAMDAC index %04X\n",stg_ramdac.index);
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switch (ramdac->index)
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{
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case 0:
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temp = 0x44;
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break;
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case 1:
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temp = 0x02;
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break;
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default:
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if (ramdac->index < 0x100) temp = ramdac->regs[ramdac->index];
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else temp = 0xff;
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break;
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}
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ramdac->index++;
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break;
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}
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ramdac->magic_count = stg_state_read[(ramdac->command & 0x10) ? 1 : 0][ramdac->magic_count & 7];
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return temp;
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case 0x3c8: case 0x3c9:
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ramdac->magic_count=0;
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break;
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}
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return svga_in(addr, svga);
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}
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