--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/interps/egobch/src/bchi.c	Sun Dec 09 19:30:08 2012 +0000
@@ -0,0 +1,163 @@
+/*
+ * Copyright (C) 2005  Gregor Richards
+ *
+ * This file is part of EgoBCh.
+ * 
+ * EgoBCh is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * EgoBCh is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with EgoBCh; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include <math.h>
+#include <stdio.h>
+
+#include "bchi.h"
+#include "egobch.h"
+
+#define LOGTWO 0.693147
+#define SETBIT(a) (7 - (int) (log((double) (a)) / LOGTWO))
+
+void binaryo()
+{
+    int i, j;
+    unsigned char vbit;
+    unsigned char *curmem;
+    for (i = -2; i <= 2; i++) {
+        curmem = mptr + i;
+        if (curmem < mem) continue;
+        for (j = 7; j >= 0; j--) {
+            vbit = 1 << j;
+            if (i == 0 && vbit == membit)
+                putchar('*');
+            if (*curmem & vbit)
+                putchar('1');
+            else
+                putchar('0');
+        }
+    }
+    putchar('\n');
+}
+
+void bch_interpret()
+{
+    int input, shft;
+    unsigned char toout;
+    struct bchi *cur;
+    
+    while (1) {
+        cur = prog + pptr;
+        /*printf("%d %d %x\n", mptr - mem, SETBIT(membit), (unsigned int) *mptr);*/
+        
+        switch (cur->cmd) {
+            case RTGL:
+                /* 1) move right */
+                membit >>= 1;
+                if (membit == 0) {
+                    membit = 0x80;
+                    mptr++;
+                }
+                
+                /* 2) check for I/O */
+                if (mptr == mem && membit == 0x04) {
+                    /* 2a) check whether to do input or output */
+                    if (*mem & 0x01) {
+                        /* 2ai) output */
+                        putchar(mem[1]);
+                        fflush(stdout);
+                    } else {
+                        /* 2aii) input */
+                        input = getchar();
+                        /* 2aiii) check for EOF */
+                        if (input == EOF) {
+                            /* mark it */
+                            *mem |= 0x02;
+                        } else {
+                            mem[1] = (char) input;
+                        }
+                    }
+                } else {
+                    /* 3) toggle */
+                    *mptr ^= membit;
+                }
+                pptr++;
+                break;
+                
+            case LFT:
+                /* move left */
+                membit <<= 1;
+                if (membit == 0) {
+                    membit = 0x01;
+                    mptr--;
+                }
+                pptr++;
+                break;
+                
+            case LPO:
+                /* loop opening */
+                if (*mptr & membit) {
+                    /* go into the loop */
+                    pptr++;
+                } else {
+                    /* jump the loop */
+                    pptr = cur->arg1 + 1;
+                }
+                break;
+                
+            case LPC:
+                /* loop close, jump to the beginning */
+                pptr = cur->arg1;
+                break;
+                
+            case OUT:
+                /* lazy_io output */
+                shft = SETBIT(membit);
+                toout = *mptr << shft;
+                
+                shft = 8 - shft;
+                toout |= mptr[1] >> shft;
+                
+                putchar(toout);
+                fflush(stdout);
+                pptr++;
+                break;
+                
+            case INP:
+                /* lazy_io input */
+                input = getchar();
+                if (input == EOF) input = 0;
+                toout = (char) input;
+                
+                /* shift it in */
+                shft = SETBIT(membit);
+                *mptr &= ~(0xFF >> shft);
+                *mptr |= toout >> shft;
+                
+                shft = 8 - shft;
+                mptr[1] &= ~(0xFF << shft);
+                mptr[1] |= toout << shft;
+                pptr++;
+                break;
+
+            case DBG:
+                binaryo();
+                pptr++;
+                break;
+                
+            case FIN:
+                return;
+                
+            default:
+                pptr++;
+        }
+    }
+}