132 lines
2.4 KiB
C
132 lines
2.4 KiB
C
#include <stdio.h>
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#ifndef _WIN32
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#include <sys/stat.h>
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#include "../perfect6502.h"
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/************************************************************
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*
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* Interface to OS Library Code / Monitor
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*
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************************************************************/
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/* imported by runtime.c */
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unsigned char A, X, Y, S, P;
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unsigned short PC;
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int N, Z, C;
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void
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init_monitor()
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{
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FILE *f;
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f = fopen("apple1basic.bin", "r");
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fread(memory + 0xE000, 1, 4096, f);
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fclose(f);
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memory[0xfffc] = 0x00;
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memory[0xfffd] = 0xE0;
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}
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void
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charout(char ch) {
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unsigned char S = readSP();
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unsigned short a = 1 + memory[0x0100+S+1] | memory[0x0100+((S+2) & 0xFF)] << 8;
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/*
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* Apple I BASIC prints every character received
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* from the terminal. UNIX terminals do this
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* anyway, so we have to avoid printing every
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* line again
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*/
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if (a==0xe2a6) /* character echo */
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return;
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if (a==0xe2b6) /* CR echo */
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return;
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/*
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* Apple I BASIC prints a line break and 6 spaces
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* after every 37 characters. UNIX terminals do
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* line breaks themselves, so ignore these
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* characters
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*/
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if (a==0xe025 && (ch==10 || ch==' '))
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return;
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/* INPUT */
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if (a==0xe182) {
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#if _WIN32
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if (!isatty(0))
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return;
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#else
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struct stat st;
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fstat(0, &st);
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if (S_ISFIFO (st.st_mode))
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return;
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#endif
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}
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#endif
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putc(ch, stdout);
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fflush(stdout);
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}
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void
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handle_monitor()
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{
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if (readRW()) {
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unsigned short a = readAddressBus();
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if ((a & 0xFF1F) == 0xD010) {
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unsigned char c = getchar();
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if (c == 10)
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c = 13;
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c |= 0x80;
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writeDataBus(c);
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}
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if ((a & 0xFF1F) == 0xD011) {
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if (readPC() == 0xE006)
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/* if the code is reading a character, we have one ready */
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writeDataBus(0x80);
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else
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/* if the code checks for a STOP condition, nothing is pressed */
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writeDataBus(0);
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}
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if ((a & 0xFF1F) == 0xD012) {
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/* 0x80 would mean we're not yet ready to receive a character */
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writeDataBus(0);
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}
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} else {
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unsigned short a = readAddressBus();
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unsigned char d = readDataBus();
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if ((a & 0xFF1F) == 0xD012) {
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unsigned char temp8 = d & 0x7F;
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if (temp8 == 13)
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temp8 = 10;
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charout(temp8);
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}
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}
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}
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int
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main()
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{
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int clk = 0;
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initAndResetChip();
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/* set up memory for user program */
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init_monitor();
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/* emulate the 6502! */
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for (;;) {
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step();
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clk = !clk;
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if (!clk)
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handle_monitor();
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chipStatus();
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//if (!(cycle % 1000)) printf("%d\n", cycle);
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};
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}
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