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/* |
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* CPUC64.cpp - 6510 (C64) emulation (line based) |
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* |
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* Frodo (C) 1994-1997,2002 Christian Bauer |
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* Frodo (C) 1994-1997,2002-2003 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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*/ |
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#if PC_IS_POINTER |
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void MOS6510::jump(uint16 adr) |
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{ |
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if (adr < 0xa000) { |
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pc = ram + adr; |
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pc_base = ram; |
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} else |
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switch (adr >> 12) { |
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case 0xa: |
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case 0xb: |
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if (basic_in) { |
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pc = basic_rom + (adr & 0x1fff); |
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pc_base = basic_rom - 0xa000; |
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} else { |
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pc = ram + adr; |
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pc_base = ram; |
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} |
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break; |
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case 0xc: |
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pc = ram + adr; |
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pc_base = ram; |
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break; |
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case 0xd: |
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if (io_in) |
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illegal_jump(pc-pc_base, adr); |
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else if (char_in) { |
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pc = char_rom + (adr & 0x0fff); |
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pc_base = char_rom - 0xd000; |
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} else { |
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pc = ram + adr; |
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pc_base = ram; |
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} |
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break; |
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case 0xe: |
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case 0xf: |
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if (kernal_in) { |
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pc = kernal_rom + (adr & 0x1fff); |
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pc_base = kernal_rom - 0xe000; |
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} else { |
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pc = ram + adr; |
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pc_base = ram; |
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} |
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break; |
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} |
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} |
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#define jump(adr) \ |
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if ((adr) < 0xa000) { \ |
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pc = ram + (adr); \ |
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pc_base = ram; \ |
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} else { \ |
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switch ((adr) >> 12) { \ |
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case 0xa: \ |
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case 0xb: \ |
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if (basic_in) { \ |
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pc = basic_rom + ((adr) & 0x1fff); \ |
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pc_base = basic_rom - 0xa000; \ |
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} else { \ |
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pc = ram + (adr); \ |
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pc_base = ram; \ |
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} \ |
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break; \ |
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case 0xc: \ |
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pc = ram + (adr); \ |
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pc_base = ram; \ |
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break; \ |
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case 0xd: \ |
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if (io_in) { \ |
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illegal_jump(pc-pc_base, (adr)); \ |
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} else if (char_in) { \ |
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pc = char_rom + ((adr) & 0x0fff); \ |
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pc_base = char_rom - 0xd000; \ |
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} else { \ |
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pc = ram + (adr); \ |
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pc_base = ram; \ |
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} \ |
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break; \ |
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case 0xe: \ |
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case 0xf: \ |
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if (kernal_in) { \ |
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pc = kernal_rom + ((adr) & 0x1fff); \ |
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pc_base = kernal_rom - 0xe000; \ |
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} else { \ |
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pc = ram + (adr); \ |
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pc_base = ram; \ |
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} \ |
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break; \ |
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} \ |
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} |
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#else |
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inline void MOS6510::jump(uint16 adr) |
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{ |
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pc = adr; |
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} |
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#define jump(adr) pc = (adr) |
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#endif |
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void MOS6510::do_adc(uint8 byte) |
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{ |
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if (!d_flag) { |
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uint16 tmp; |
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|
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// Binary mode |
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tmp = a + byte + (c_flag ? 1 : 0); |
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uint16 tmp = a + (byte) + (c_flag ? 1 : 0); |
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c_flag = tmp > 0xff; |
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v_flag = !((a ^ byte) & 0x80) && ((a ^ tmp) & 0x80); |
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v_flag = !((a ^ (byte)) & 0x80) && ((a ^ tmp) & 0x80); |
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z_flag = n_flag = a = tmp; |
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} else { |
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uint16 al, ah; |
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|
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// Decimal mode |
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al = (a & 0x0f) + (byte & 0x0f) + (c_flag ? 1 : 0); // Calculate lower nybble |
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if (al > 9) al += 6; // BCD fixup for lower nybble |
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|
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ah = (a >> 4) + (byte >> 4); // Calculate upper nybble |
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al = (a & 0x0f) + ((byte) & 0x0f) + (c_flag ? 1 : 0); |
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if (al > 9) al += 6; |
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ah = (a >> 4) + ((byte) >> 4); |
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if (al > 0x0f) ah++; |
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|
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z_flag = a + byte + (c_flag ? 1 : 0); // Set flags |
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n_flag = ah << 4; // Only highest bit used |
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v_flag = (((ah << 4) ^ a) & 0x80) && !((a ^ byte) & 0x80); |
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|
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if (ah > 9) ah += 6; // BCD fixup for upper nybble |
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c_flag = ah > 0x0f; // Set carry flag |
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a = (ah << 4) | (al & 0x0f); // Compose result |
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z_flag = a + (byte) + (c_flag ? 1 : 0); |
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n_flag = ah << 4; |
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v_flag = (((ah << 4) ^ a) & 0x80) && !((a ^ (byte)) & 0x80); |
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if (ah > 9) ah += 6; |
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c_flag = ah > 0x0f; |
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a = (ah << 4) | (al & 0x0f); |
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} |
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} |
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void MOS6510::do_sbc(uint8 byte) |
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{ |
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uint16 tmp = a - byte - (c_flag ? 0 : 1); |
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uint16 tmp = a - (byte) - (c_flag ? 0 : 1); |
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if (!d_flag) { |
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|
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// Binary mode |
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c_flag = tmp < 0x100; |
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v_flag = ((a ^ tmp) & 0x80) && ((a ^ byte) & 0x80); |
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v_flag = ((a ^ tmp) & 0x80) && ((a ^ (byte)) & 0x80); |
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z_flag = n_flag = a = tmp; |
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} else { |
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uint16 al, ah; |
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|
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// Decimal mode |
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al = (a & 0x0f) - (byte & 0x0f) - (c_flag ? 0 : 1); // Calculate lower nybble |
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ah = (a >> 4) - (byte >> 4); // Calculate upper nybble |
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al = (a & 0x0f) - ((byte) & 0x0f) - (c_flag ? 0 : 1); |
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ah = (a >> 4) - ((byte) >> 4); |
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if (al & 0x10) { |
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al -= 6; // BCD fixup for lower nybble |
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al -= 6; |
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ah--; |
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} |
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if (ah & 0x10) ah -= 6; // BCD fixup for upper nybble |
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|
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c_flag = tmp < 0x100; // Set flags |
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v_flag = ((a ^ tmp) & 0x80) && ((a ^ byte) & 0x80); |
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if (ah & 0x10) ah -= 6; |
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c_flag = tmp < 0x100; |
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v_flag = ((a ^ tmp) & 0x80) && ((a ^ (byte)) & 0x80); |
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z_flag = n_flag = tmp; |
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a = (ah << 4) | (al & 0x0f); // Compose result |
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a = (ah << 4) | (al & 0x0f); |
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} |
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} |
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if (i_flag) s->p |= 0x04; |
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if (!z_flag) s->p |= 0x02; |
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if (c_flag) s->p |= 0x01; |
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|
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s->ddr = ram[0]; |
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s->pr = ram[1] & 0x3f; |
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// Any pending interrupts? |
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if (interrupt.intr_any) { |
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handle_int: |
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if (interrupt.intr[INT_RESET]) |
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if (interrupt.intr[INT_RESET]) { |
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Reset(); |
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else if (interrupt.intr[INT_NMI]) { |
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} else if (interrupt.intr[INT_NMI]) { |
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interrupt.intr[INT_NMI] = false; // Simulate an edge-triggered input |
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#if PC_IS_POINTER |
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push_byte((pc-pc_base) >> 8); push_byte(pc-pc_base); |
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#endif |
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push_flags(false); |
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i_flag = true; |
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jump(read_word(0xfffa)); |
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adr = read_word(0xfffa); |
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jump(adr); |
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last_cycles = 7; |
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} else if ((interrupt.intr[INT_VICIRQ] || interrupt.intr[INT_CIAIRQ]) && !i_flag) { |
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#endif |
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push_flags(false); |
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i_flag = true; |
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jump(read_word(0xfffe)); |
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adr = read_word(0xfffe); |
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jump(adr); |
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last_cycles = 7; |
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} |
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} |
