38 lines
969 B
C
38 lines
969 B
C
/*INTEL 82355 MCR emulation
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This chip was used as part of many 386 chipsets
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It controls memory addressing and shadowing*/
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#include "ibm.h"
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int nextreg6;
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uint8_t mcr22;
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int mcrlock,mcrfirst;
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void resetmcr()
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{
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mcrlock=0;
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mcrfirst=1;
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shadowbios=0;
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}
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void writemcr(uint16_t addr, uint8_t val)
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{
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printf("Write MCR %04X %02X %04X:%04X\n",addr,val,CS,cpu_state.pc);
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switch (addr)
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{
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case 0x22:
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if (val==6 && mcr22==6) nextreg6=1;
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else nextreg6=0;
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// if ((val&1) && (mcr22&1)) shadowbios=1;
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// if (!(val&1) && !(mcr22&1)) shadowbios=0;
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// if (!mcrfirst) shadowbios=val&1;
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// mcrfirst=0;
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// dumpregs();
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// exit(-1);
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break;
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case 0x23:
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if (nextreg6) shadowbios=!val;
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break;
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}
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mcr22=val;
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}
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