Added simple WCSA

[SXSI/TextCollection.git] / swcsa / utils / basics.c

diff --git a/swcsa/utils/basics.c b/swcsa/utils/basics.c
new file mode 100755 (executable)
index 0000000..f213ed6
--- /dev/null
+++ b/swcsa/utils/basics.c
@@ -0,0 +1,107 @@
+
+// Basics
+
+// #include "basics.h" included later to avoid macro recursion for malloc
+#include <sys/types.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+               // Memory management
+       
+       void *Malloc (int n)
+       
+          { void *p;
+            if (n == 0) return NULL;
+            p = (void*) malloc (n);
+            if (p == NULL)
+               { fprintf (stderr,"Could not allocate %i bytes\n",n);
+                 exit(1);
+               }
+            return p;
+          }
+       
+       void Free (void *p)
+       
+          { if (p) free (p); 
+          }
+       
+       void *Realloc (void *p, int n)
+       
+          { if (p == NULL) return Malloc (n);
+            if (n == 0) { Free(p); return NULL; }
+            p = (void*) realloc (p,n);
+            if (p == NULL)
+               { fprintf (stderr,"Could not allocate %i bytes\n",n);
+                 exit(1);
+               }
+            return p;
+          }
+
+#include "basics.h"
+
+        // bits needed to represent a number between 0 and n
+
+uint bits (uint n)
+
+   { uint b = 0;
+     while (n)
+       { b++; n >>= 1; }
+     return b;
+   }
+
+        // returns e[p..p+len-1], assuming len <= W
+
+uint bitread (uint *e, uint p, uint len)
+
+   { uint answ;
+     e += p/W; p %= W;
+     answ = *e >> p;
+     if (len == W)
+         { if (p) answ |= (*(e+1)) << (W-p);
+         }
+     else { if (p+len > W) answ |= (*(e+1)) << (W-p);
+            answ &= (1<<len)-1;
+         }
+     return answ;
+   }
+
+
+       // writes e[p..p+len-1] = s, len <= W
+
+void bitwrite (register uint *e, register uint p, 
+              register uint len, register uint s)
+
+   { e += p/W; p %= W;
+     if (len == W)
+         { *e |= (*e & ((1<<p)-1)) | (s << p);
+            if (!p) return;
+            e++;
+            *e = (*e & ~((1<<p)-1)) | (s >> (W-p));
+         }
+     else { if (p+len <= W)
+              { *e = (*e & ~(((1<<len)-1)<<p)) | (s << p);
+                return;
+              }
+           *e = (*e & ((1<<p)-1)) | (s << p);
+            e++; len -= W-p;
+            *e = (*e & ~((1<<len)-1)) | (s >> (W-p));
+         }
+   }
+       // writes e[p..p+len-1] = 0
+
+void bitzero (register uint *e, register uint p, 
+              register uint len)
+
+   { e += p/W; p %= W;
+     if (p+len >= W)
+       { *e &= ~((1<<p)-1);
+         len -= p;
+         e++; p = 0;
+       }
+     while (len >= W)
+       { *e++ = 0;
+         len -= W;
+       }
+     if (len > 0)
+       *e &= ~(((1<<len)-1)<<p);
+   }