1 line
3.9 KiB
C
Executable File
1 line
3.9 KiB
C
Executable File
/*
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SCSIEMDV.c
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Copyright (C) 2004 Philip Cummins, Paul C. Pratt
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You can redistribute this file and/or modify it under the terms
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of version 2 of the GNU General Public License as published by
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the Free Software Foundation. You should have received a copy
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of the license along with this file; see the file COPYING.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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license for more details.
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*/
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/*
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Small Computer System Interface EMulated DeVice
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Emulates the SCSI found in the Mac Plus.
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This code adapted from "SCSI.c" in vMac by Philip Cummins.
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*/
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/* NCR5380 chip emulation by Yoav Shadmi, 1998 */
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#ifndef AllFiles
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#include "SYSDEPNS.h"
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#include "ENDIANAC.h"
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#include "MYOSGLUE.h"
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#include "EMCONFIG.h"
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#include "GLOBGLUE.h"
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#endif
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#include "SCSIEMDV.h"
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#define scsiRd 0x00
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#define scsiWr 0x01
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#define sCDR 0x00 /* current scsi data register (r/o) */
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#define sODR 0x00 /* output data register (w/o) */
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#define sICR 0x02 /* initiator command register (r/w) */
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#define sMR 0x04 /* mode register (r/w) */
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#define sTCR 0x06 /* target command register (r/w) */
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#define sCSR 0x08 /* current SCSI bus status (r/o) */
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#define sSER 0x08 /* select enable register (w/o) */
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#define sBSR 0x0A /* bus and status register (r/o) */
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#define sDMAtx 0x0A /* start DMA send (w/o) */
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#define sIDR 0x0C /* input data register (r/o) */
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#define sTDMArx 0x0C /* start DMA target receive (w/o) */
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#define sRESET 0x0E /* reset parity/interrupt (r/o) */
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#define sIDMArx 0x0E /* start DMA initiator receive (w/o) */
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#define kSCSI_Size 0x00010
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LOCALVAR ui3b SCSI[kSCSI_Size];
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GLOBALPROC SCSI_Reset(void)
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{
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int i;
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for (i = 0; i < kSCSI_Size; i++) {
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SCSI[i] = 0;
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}
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}
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LOCALPROC SCSI_BusReset(void)
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{
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SCSI[scsiRd + sCDR] = 0;
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SCSI[scsiWr + sODR] = 0;
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SCSI[scsiRd + sICR] = 0x80;
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SCSI[scsiWr + sICR] &= 0x80;
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SCSI[scsiRd + sMR] &= 0x40;
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SCSI[scsiWr + sMR] &= 0x40;
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SCSI[scsiRd + sTCR] = 0;
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SCSI[scsiWr + sTCR] = 0;
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SCSI[scsiRd + sCSR] = 0x80;
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SCSI[scsiWr + sSER] = 0;
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SCSI[scsiRd + sBSR] = 0x10;
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SCSI[scsiWr + sDMAtx] = 0;
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SCSI[scsiRd + sIDR] = 0;
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SCSI[scsiWr + sTDMArx] = 0;
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SCSI[scsiRd + sRESET] = 0;
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SCSI[scsiWr + sIDMArx] = 0;
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#if 0
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SCSI[scsiRd + sODR + dackWr] = 0;
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SCSI[scsiWr + sIDR + dackRd] = 0;
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#endif
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/* The missing piece of the puzzle.. :) */
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put_ram_word(0xb22, get_ram_word(0xb22) | 0x8000);
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}
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LOCALPROC SCSI_Check(void)
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{
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/*
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The arbitration select/reselect scenario
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[stub.. doesn't really work...]
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*/
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if ((SCSI[scsiWr + sODR] >> 7) == 1) {
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/* Check if the Mac tries to be an initiator */
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if ((SCSI[scsiWr + sMR] & 1) == 1) {
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/* the Mac set arbitration in progress */
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/*
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stub! tell the mac that there
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is arbitration in progress...
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*/
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SCSI[scsiRd + sICR] |= 0x40;
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/* ... that we didn't lose arbitration ... */
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SCSI[scsiRd + sICR] &= ~ 0x20;
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/*
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... and that there isn't a higher priority ID present...
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*/
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SCSI[scsiRd + sCDR] = 0x00;
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/*
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... the arbitration and selection/reselection is
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complete. the initiator tries to connect to the SCSI
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device, fails and returns after timeout.
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*/
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}
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}
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/* check the chip registers, AS SET BY THE CPU */
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if ((SCSI[scsiWr + sICR] >> 7) == 1) {
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/* Check Assert RST */
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SCSI_BusReset();
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} else {
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SCSI[scsiRd + sICR] &= ~ 0x80;
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SCSI[scsiRd + sCSR] &= ~ 0x80;
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}
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if ((SCSI[scsiWr + sICR] >> 2) == 1) {
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/* Check Assert SEL */
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SCSI[scsiRd + sCSR] |= 0x02;
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SCSI[scsiRd + sBSR] = 0x10;
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} else {
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SCSI[scsiRd + sCSR] &= ~ 0x02;
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}
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}
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GLOBALFUNC ui5b SCSI_Access(ui5b Data, blnr WriteMem, CPTR addr)
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{
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if (addr < (kSCSI_Size / 2)) {
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addr *= 2;
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if (WriteMem) {
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SCSI[addr + 1] = Data;
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SCSI_Check();
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} else {
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Data = SCSI[addr];
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}
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}
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return Data;
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}
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