o cleanup

tools/bsnes/lib/nall/lzss.hpp

@@ -0,0 +1,81 @@
+#ifndef NALL_LZSS_HPP
+#define NALL_LZSS_HPP
+
+#include <nall/array.hpp>
+#include <nall/new.hpp>
+#include <nall/stdint.hpp>
+
+namespace nall {
+  class lzss {
+  public:
+    static bool encode(uint8_t *&output, unsigned &outlength, const uint8_t *input, unsigned inlength) {
+      output = new(zeromemory) uint8_t[inlength * 9 / 8 + 9];
+
+      unsigned i = 0, o = 0;
+      while(i < inlength) {
+        unsigned flagoffset = o++;
+        uint8_t flag = 0x00;
+
+        for(unsigned b = 0; b < 8 && i < inlength; b++) {
+          unsigned longest = 0, pointer;
+          for(unsigned index = 1; index < 4096; index++) {
+            unsigned count = 0;
+            while(true) {
+              if(count >= 15 + 3) break;                               //verify pattern match is not longer than max length
+              if(i + count >= inlength) break;                         //verify pattern match does not read past end of input
+              if(i + count < index) break;                             //verify read is not before start of input
+              if(input[i + count] != input[i + count - index]) break;  //verify pattern still matches
+              count++;
+            }
+
+            if(count > longest) {
+              longest = count;
+              pointer = index;
+            }
+          }
+
+          if(longest < 3) output[o++] = input[i++];
+          else {
+            flag |= 1 << b;
+            uint16_t x = ((longest - 3) << 12) + pointer;
+            output[o++] = x;
+            output[o++] = x >> 8;
+            i += longest;
+          }
+        }
+
+        output[flagoffset] = flag;
+      }
+
+      outlength = o;
+      return true;
+    }
+
+    static bool decode(uint8_t *&output, const uint8_t *input, unsigned length) {
+      output = new(zeromemory) uint8_t[length];
+
+      unsigned i = 0, o = 0;
+      while(o < length) {
+        uint8_t flag = input[i++];
+
+        for(unsigned b = 0; b < 8 && o < length; b++) {
+          if(!(flag & (1 << b))) output[o++] = input[i++];
+          else {
+            uint16_t offset = input[i++];
+            offset += input[i++] << 8;
+            uint16_t lookuplength = (offset >> 12) + 3;
+            offset &= 4095;
+            for(unsigned index = 0; index < lookuplength && o + index < length; index++) {
+              output[o + index] = output[o + index - offset];
+            }
+            o += lookuplength;
+          }
+        }
+      }
+
+      return true;
+    }
+  };
+}
+
+#endif