65 lines
1.6 KiB
C
65 lines
1.6 KiB
C
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/*
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* external.c
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*
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* This file is part of Emu48
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*
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* Copyright (C) 1995 Sebastien Carlier
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*
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*/
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#include "pch.h"
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#include "Emu48.h"
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// 02.02.98 cg, new, memory address for flags -53 to -56
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#define SFLAG53_56 ((cCurrentRomType=='S')?0x706D2:0x80850)
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static __inline VOID Return(CHIPSET* w)
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{
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w->rstkp=(w->rstkp-1)&7;
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w->pc = w->rstk[w->rstkp];
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w->rstk[w->rstkp] = 0;
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return;
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}
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VOID External(CHIPSET* w)
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{
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if (w->pc==0x017A6) // Beep
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{
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// begin with patch
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// 02.02.98 cg, changed for better emulation
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BYTE fbeep;
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DWORD freq,dur;
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freq = Npack(w->D,5); // frequency in Hz
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dur = Npack(w->C,5); // duration in ms
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Nread(&fbeep,SFLAG53_56,1); // fetch system flags -53 to -56
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w->carry = TRUE; // 22.07.98 cg, setting of no beep
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if (!(fbeep & 0x8) && freq) // bit -56 clear and frequency > 0 Hz
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{
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if (freq < 37) freq = 37; // low limit of freqency (NT)
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if (freq > 4400) freq = 4400; // 22.07.98 cg, high limit of HP (SX)
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if (dur > 1048575) // 22.07.98 cg, high limit of HP (SX)
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dur = 1048575;
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Beep(freq,dur); // NT: ok, Windows 95: default sound or standard system beep
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// 22.07.98 cg, estimate cpu cycles for beeping time (2MHz / 4MHz)
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w->cycles += dur * ((cCurrentRomType=='S') ? 2000 : 4000);
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// original routine return with...
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w->P = 0; // 22.07.98 cg, P=0
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w->intk = TRUE; // 22.07.98 cg, INTON
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w->carry = FALSE; // 22.07.98 cg, RTNCC
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}
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// MessageBeep(0xFFFFFFFF); // original, replaced
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// continue with original part
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//Beep(600,50);
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Return(w);
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return;
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}
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w->pc +=4;
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return;
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}
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