56 lines
1.4 KiB
C++
56 lines
1.4 KiB
C++
#include "cpuboard.hpp"
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#include <cstdio>
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void Assigner::noteOn() {
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// called from serial interrupt handler
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// sets or clears a bit in the "MIDI Key pressed" bitfield
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// note that RAM addresses normally set to 0xff40 are reduced to 0x0040
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// 06ca
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a = ram[0x3e]; // first byte is note value
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c = 0x40; // fake velocity
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// bring note into range
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// 06cc
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if (a <= 0x17) a += 12;
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// 06d0
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if (a >= 0x6d) a -= 12;
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// 06d4 subtract transpose from ffbe
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// 06d7 mov b,a; slr b; slr b; slr b
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b = a >> 3;
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a &= 0x07;
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// 06e0 note on?
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if (ram[0x4e] != 0x90) goto h06f9; // no, skip to note off
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// 06e4 velocity zero?
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if (c == 0) goto h06f9; // yes, skip to note off
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// otherwise handle note on
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// 06e8 lxi hl,$0008; ldax (a+hl) for table of bits
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a = 1 << a;
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c = a;
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hl = 0x0040; // note bit flags
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a = ram[hl + b]; // byte pointed to by upper part
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a |= c; // or in the bit value
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ram[hl+b] = a; // save it in RAM
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// 06f4 mviw $003f, $01 expect two bytes; jre $064c return from interrupt
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return;
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h06f9: // note off
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a = 0xff ^ (1 << a);
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c = a;
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hl = 0x0040; // note bit flags
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a = ram[hl + b]; // byte pointed to by upper part
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a &= c; // mask off the bit
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ram[hl+b] = a; // save it in RAM
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return;
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} |