455 lines
11 KiB
C
455 lines
11 KiB
C
#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include "vm.h"
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// Port for block reads. Each read or write has to be done in 5 IO writes:
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// 1 - r/w. 1 for read, 2 for write.
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// 2 - blkid MSB
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// 3 - blkid LSB
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// 4 - dest addr MSB
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// 5 - dest addr LSB
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#define BLK_PORT 0x03
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static VM vm;
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static uint64_t blkop = 0; // 5 bytes
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static FILE *blkfp;
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// Read single byte from I/O handler, if set. addr is a word only because of
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// Forth's cell size, but can't actually address more than a byte-ful of ports.
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static byte io_read(word addr)
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{
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addr &= 0xff;
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IORD fn = vm.iord[addr];
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if (fn != NULL) {
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return fn();
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} else {
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fprintf(stderr, "Out of bounds I/O read: %d\n", addr);
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return 0;
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}
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}
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static void io_write(word addr, byte val)
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{
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addr &= 0xff;
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IOWR fn = vm.iowr[addr];
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if (fn != NULL) {
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fn(val);
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} else {
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fprintf(stderr, "Out of bounds I/O write: %d / %d (0x%x)\n", addr, val, val);
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}
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}
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// I/O hook to read/write a chunk of 1024 byte to blkfs at specified blkid.
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// This is used by EFS@ and EFS! in xcomp.fs.
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// See comment above BLK_PORT define for poking convention.
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static void iowr_blk(byte val)
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{
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blkop <<= 8;
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blkop |= val;
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byte rw = blkop >> 32;
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if (rw) {
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word blkid = (blkop >> 16);
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word dest = blkop & 0xffff;
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blkop = 0;
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fseek(blkfp, blkid*1024, SEEK_SET);
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if (rw==2) { // write
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fwrite(&vm.mem[dest], 1024, 1, blkfp);
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} else { // read
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fread(&vm.mem[dest], 1024, 1, blkfp);
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}
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}
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}
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// get/set word from/to memory
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static word gw(word addr) { return vm.mem[addr+(word)1] << 8 | vm.mem[addr]; }
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static void sw(word addr, word val) {
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vm.mem[addr] = val;
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vm.mem[addr+(word)1] = val >> 8;
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}
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// pop word from SP
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static word pop() {
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if (vm.uflw) return 0;
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if (vm.SP >= SP_ADDR) { vm.uflw = true; return 0; }
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return vm.mem[vm.SP++] | vm.mem[vm.SP++] << 8;
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}
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// push word to SP
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static void push(word x) {
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vm.SP -= 2;
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if (vm.SP <= vm.RS) {
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vm.oflw = true; vm.SP = SP_ADDR; vm.RS = RS_ADDR;
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return;
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}
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sw(vm.SP, x);
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if (vm.SP < vm.minSP) { vm.minSP = vm.SP; }
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}
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// pop word from RS
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static word popRS() {
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if (vm.uflw) return 0;
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if (vm.RS <= RS_ADDR) { vm.uflw = true; return 0; }
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word x = gw(vm.RS); vm.RS -= 2; return x;
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}
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// push word to RS
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static void pushRS(word val) {
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vm.RS += 2;
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if (vm.SP <= vm.RS) {
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vm.oflw = true; vm.SP = SP_ADDR; vm.RS = RS_ADDR;
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return;
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}
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sw(vm.RS, val);
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if (vm.RS > vm.maxRS) { vm.maxRS = vm.RS; }
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}
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// The functions below directly map to native forth words defined in the
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// dictionary (doc/dict.txt)
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static void execute(word wordref) {
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byte wtype = vm.mem[wordref];
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switch (wtype) {
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case 0: // native
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vm.nativew[vm.mem[wordref+(word)1]]();
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break;
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case 1: // compiled
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pushRS(vm.IP);
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vm.IP = wordref+1;
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break;
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case 2: // cell
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push(wordref+1);
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break;
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case 3: // does
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push(wordref+1);
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pushRS(vm.IP);
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vm.IP = gw(wordref+3);
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break;
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case 4: // alias
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execute(gw(wordref+1));
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break;
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case 5: // switch
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execute(gw(gw(wordref+1)));
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break;
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}
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}
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static word find(word daddr, word waddr) {
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byte len = vm.mem[waddr];
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waddr++;
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while (1) {
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if ((vm.mem[daddr-(word)1] & 0x7f) == len) {
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word d = daddr-3-len;
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// Sanity check
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if ((waddr+len >= MEMSIZE) || (d+len) >= MEMSIZE) return 0;
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if (strncmp(&vm.mem[waddr], &vm.mem[d], len) == 0) {
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return daddr;
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}
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}
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daddr -= 3;
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word offset = gw(daddr);
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if (offset) {
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daddr -= offset;
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} else {
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return 0;
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}
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}
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}
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static void EXIT() { vm.IP = popRS(); }
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static void _br_() {
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word off = vm.mem[vm.IP];
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if (off > 0x7f ) { off -= 0x100; }
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vm.IP += off;
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}
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static void _cbr_() { if (!pop()) { _br_(); } else { vm.IP++; } }
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static void _loop_() {
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word I = gw(vm.RS); I++; sw(vm.RS, I);
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if (I == gw(vm.RS-2)) { // don't branch
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popRS(); popRS();
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vm.IP++;
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} else { // branch
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_br_();
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}
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}
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static void SP_to_R_2() { word x = pop(); pushRS(pop()); pushRS(x); }
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static void nlit() { push(gw(vm.IP)); vm.IP += 2; }
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static void slit() { push(vm.IP); vm.IP += vm.mem[vm.IP] + 1; }
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static void SP_to_R() { pushRS(pop()); }
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static void R_to_SP() { push(popRS()); }
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static void R_to_SP_2() { word x = popRS(); push(popRS()); push(x); }
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static void EXECUTE() { execute(pop()); }
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static void ROT() { // a b c -- b c a
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word c = pop(); word b = pop(); word a = pop();
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push(b); push(c); push(a);
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}
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static void ROTR() { // a b c -- c a b
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word c = pop(); word b = pop(); word a = pop();
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push(c); push(a); push(b);
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}
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static void DUP() { // a -- a a
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word a = pop(); push(a); push(a);
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}
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static void CDUP() {
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word a = pop(); push(a); if (a) { push(a); }
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}
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static void DROP() { pop(); }
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static void SWAP() { // a b -- b a
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word b = pop(); word a = pop();
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push(b); push(a);
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}
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static void OVER() { // a b -- a b a
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word b = pop(); word a = pop();
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push(a); push(b); push(a);
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}
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static void PICK() {
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word x = pop();
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push(gw(vm.SP+x*2));
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}
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static void _roll_() { // "1 2 3 4 4 (roll)" --> "1 3 4 4"
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word x = pop();
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while (x) { vm.mem[vm.SP+x+(word)2] = vm.mem[vm.SP+x]; x--; }
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}
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static void DROP2() { pop(); pop(); }
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static void DUP2() { // a b -- a b a b
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word b = pop(); word a = pop();
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push(a); push(b); push(a); push(b);
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}
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static void S0() { push(SP_ADDR); }
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static void Saddr() { push(vm.SP); }
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static void AND() { push(pop() & pop()); }
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static void OR() { push(pop() | pop()); }
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static void XOR() { push(pop() ^ pop()); }
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static void NOT() { push(!pop()); }
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static void PLUS() { push(pop() + pop()); }
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static void MINUS() {
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word b = pop(); word a = pop();
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push(a - b);
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}
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static void MULT() { push(pop() * pop()); }
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static void DIVMOD() {
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word b = pop(); word a = pop();
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push(a % b); push(a / b);
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}
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static void STORE() {
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word a = pop(); word val = pop();
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sw(a, val);
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}
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static void FETCH() { push(gw(pop())); }
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static void CSTORE() {
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word a = pop(); word val = pop();
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vm.mem[a] = val;
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}
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static void CFETCH() { push(vm.mem[pop()]); }
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static void IO_OUT() {
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word a = pop(); word val = pop();
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io_write(a, val);
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}
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static void IO_IN() { push(io_read(pop())); }
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static void RI() { push(gw(vm.RS)); }
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static void RI_() { push(gw(vm.RS-2)); }
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static void RJ() { push(gw(vm.RS-4)); }
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static void BYE() { vm.running = false; }
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static void _resSP_() { vm.SP = SP_ADDR; }
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static void _resRS_() { vm.RS = RS_ADDR; }
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static void Seq() {
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word s1 = pop(); word s2 = pop();
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byte len = vm.mem[s1];
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if (len == vm.mem[s2]) {
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s1++; s2++;
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push(strncmp(&vm.mem[s1], &vm.mem[s2], len) == 0);
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} else {
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push(0);
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}
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}
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static void CMP() {
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word b = pop(); word a = pop();
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if (a == b) { push(0); } else if (a > b) { push(1); } else { push(-1); }
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}
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static void _find() {
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word waddr = pop(); word daddr = pop();
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daddr = find(daddr, waddr);
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if (daddr) {
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push(daddr); push(1);
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} else {
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push(waddr); push(0);
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}
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}
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static void ZERO() { push(0); }
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static void ONE() { push(1); }
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static void MONE() { push(-1); }
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static void PLUS1() { push(pop()+1); }
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static void MINUS1() { push(pop()-1); }
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static void MINUS2() { push(pop()-2); }
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static void PLUS2() { push(pop()+2); }
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static void RSHIFT() { word u = pop(); push(pop()>>u); }
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static void LSHIFT() { word u = pop(); push(pop()<<u); }
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static void TICKS() { usleep(pop()); }
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static void SPLITL() {
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word n = pop(); push(n>>8); push(n&0xff); }
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static void SPLITM() {
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word n = pop(); push(n&0xff); push(n>>8); }
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static void native(NativeWord func) {
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vm.nativew[vm.nativew_count++] = func;
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}
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VM* VM_init(char *bin_path, char *blkfs_path)
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{
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fprintf(stderr, "Using blkfs %s\n", blkfs_path);
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blkfp = fopen(blkfs_path, "r+");
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if (!blkfp) {
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fprintf(stderr, "Can't open\n");
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return NULL;
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}
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fseek(blkfp, 0, SEEK_END);
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if (ftell(blkfp) < 100 * 1024) {
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fclose(blkfp);
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fprintf(stderr, "emul/blkfs too small, something's wrong, aborting.\n");
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return NULL;
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}
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fseek(blkfp, 0, SEEK_SET);
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FILE *bfp = fopen(bin_path, "r");
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if (!bfp) {
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fprintf(stderr, "Can't open forth.bin\n");
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return NULL;
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}
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int i = 0;
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int c = getc(bfp);
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while (c != EOF) {
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vm.mem[i++] = c;
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c = getc(bfp);
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}
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fclose(bfp);
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// initialize rest of memory with random data. Many, many bugs we've seen in
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// Collapse OS were caused by bad initialization and weren't reproducable
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// in CVM because it has a neat zeroed-out memory. Let's make bugs easier
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// to spot.
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while (i<0x10000) {
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vm.mem[i++] = random();
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}
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vm.SP = SP_ADDR;
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vm.RS = RS_ADDR;
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vm.minSP = SP_ADDR;
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vm.maxRS = RS_ADDR;
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vm.nativew_count = 0;
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for (int i=0; i<0x100; i++) {
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vm.iord[i] = NULL;
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vm.iowr[i] = NULL;
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}
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vm.iowr[BLK_PORT] = iowr_blk;
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// Added in the same order as in xcomp.fs
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native(EXIT);
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native(_br_);
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native(_cbr_);
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native(_loop_);
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native(nlit);
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native(slit);
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native(SP_to_R);
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native(R_to_SP);
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native(SP_to_R_2);
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native(R_to_SP_2);
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native(EXECUTE);
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native(ROT);
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native(DUP);
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native(CDUP);
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native(DROP);
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native(SWAP);
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native(OVER);
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native(PICK);
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native(_roll_);
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native(DROP2);
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native(DUP2);
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native(S0);
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native(Saddr);
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native(AND);
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native(OR);
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native(XOR);
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native(NOT);
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native(PLUS);
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native(MINUS);
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native(MULT);
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native(DIVMOD);
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native(STORE);
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native(FETCH);
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native(CSTORE);
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native(CFETCH);
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native(IO_OUT);
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native(IO_IN);
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native(RI);
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native(RI_);
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native(RJ);
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native(BYE);
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native(_resSP_);
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native(_resRS_);
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native(Seq);
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native(CMP);
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native(_find);
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native(ZERO);
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native(ONE);
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native(MONE);
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native(PLUS1);
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native(MINUS1);
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native(PLUS2);
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native(MINUS2);
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native(RSHIFT);
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native(LSHIFT);
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native(TICKS);
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native(ROTR);
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native(SPLITL);
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native(SPLITM);
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vm.IP = gw(0x04) + 1; // BOOT
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sw(SYSVARS+0x02, gw(0x08)); // CURRENT
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sw(SYSVARS+0x04, gw(0x08)); // HERE
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vm.uflw = false;
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vm.oflw = false;
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vm.running = true;
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return &vm;
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}
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void VM_deinit()
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{
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fclose(blkfp);
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}
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bool VM_steps(int n) {
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if (!vm.running) {
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fprintf(stderr, "machine halted!\n");
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return false;
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}
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while (n && vm.running) {
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word wordref = gw(vm.IP);
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vm.IP += 2;
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execute(wordref);
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if (vm.uflw) {
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vm.uflw = false;
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execute(gw(0x06)); /* uflw */
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}
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if (vm.oflw) {
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vm.oflw = false;
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execute(gw(0x13)); /* oflw */
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}
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n--;
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}
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return vm.running;
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}
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void VM_memdump() {
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fprintf(stderr, "Dumping memory to memdump. IP %04x\n", vm.IP);
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FILE *fp = fopen("memdump", "w");
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fwrite(vm.mem, 0x10000, 1, fp);
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fclose(fp);
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}
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void VM_debugstr(char *s) {
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sprintf(s, "SP %04x (%04x) RS %04x (%04x)",
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vm.SP, vm.minSP, vm.RS, vm.maxRS);
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}
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void VM_printdbg() {
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char buf[0x100];
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VM_debugstr(buf);
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fprintf(stderr, "%s\n", buf);
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}
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