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/* |
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* CPUC64_SC.cpp - Single-cycle 6510 (C64) emulation |
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* |
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* Frodo (C) 1994-1997,2002-2005 Christian Bauer |
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* Frodo (C) 1994-1997,2002-2009 Christian Bauer |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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ddr = s->ddr; |
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pr = s->pr; |
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pr_out = 0; // FIXME: should be saved in MOS6510State |
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new_config(); |
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pc = s->pc; |
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void MOS6510::new_config(void) |
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{ |
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uint8 port = ~ddr | pr; |
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pr_out = (pr_out & ~ddr) | (pr & ddr); |
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uint8 port = pr | ~ddr; |
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basic_in = (port & 3) == 3; |
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kernal_in = port & 2; |
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uint8 MOS6510::read_byte(uint16 adr) |
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{ |
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if (adr < 0xa000) { |
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if (adr >= 2) |
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if (adr >= 2) { |
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return ram[adr]; |
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else if (adr == 0) |
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} else if (adr == 0) { |
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return ddr; |
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else |
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return (ddr & pr) | (~ddr & 0x17); |
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} else { |
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uint8 byte = (pr | ~ddr) & (pr_out | 0x17); |
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if (!(ddr & 0x20)) |
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byte &= 0xdf; |
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return byte; |
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} |
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} else |
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return read_byte_io(adr); |
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} |
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ram[0x8004] = 0; |
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// Initialize extra 6510 registers and memory configuration |
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ddr = pr = 0; |
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ddr = pr = pr_out = 0; |
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new_config(); |
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// Clear all interrupt lines |
