--- a
+++ b/src/decoder.c
@@ -0,0 +1,706 @@
+/*
+ * Copyright (C) 2000, 2001 Martin Norbäck, Hĺkan Hjort
+ * 
+ * This file is part of libdvdnav, a DVD navigation library. It is modified
+ * from a file originally part of the Ogle DVD player.
+ * 
+ * libdvdnav 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.
+ * 
+ * libdvdnav 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA
+ *
+ * $Id$
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdio.h>
+#include <inttypes.h>
+#include <string.h>  /* For memset */
+#include <dvdread/ifo_types.h> /* vm_cmd_t */
+#include "vmcmd.h"
+#include "decoder.h"
+
+#ifndef bool
+typedef int bool;
+#endif
+
+typedef struct
+{
+  uint8_t bits[8];
+  uint8_t examined[8];
+} cmd_t;
+
+/*  Fix theses two.. pass as parameters instead. */
+static cmd_t cmd;
+static registers_t *state;
+
+/* Get count bits of command from byte and bit position. */
+static uint32_t bits(int byte, int bit, int count) {
+  uint32_t val = 0;
+  int bit_mask;
+  
+  while(count--) {
+    if(bit > 7) {
+      bit = 0;
+      byte++;
+    }
+    bit_mask = 0x01 << (7 - bit);
+    val <<= 1;
+    if(cmd.bits[byte] & bit_mask)
+      val |= 1;
+    cmd.examined[byte] |= bit_mask;
+    bit++;
+  }
+  return val;
+}
+
+
+/* Eval register code, can either be system or general register.
+   SXXX_XXXX, where S is 1 if it is system register. */
+static uint16_t eval_reg(uint8_t reg) {
+  if(reg & 0x80) {
+    return state->SPRM[reg & 0x1f]; /*  FIXME max 24 not 32 */
+  } else {
+    return state->GPRM[reg & 0x0f];
+  }
+}
+
+/* Eval register or immediate data.
+   AAAA_AAAA BBBB_BBBB, if immediate use all 16 bits for data else use
+   lower eight bits for the system or general purpose register. */
+static uint16_t eval_reg_or_data(int imm, int byte) {
+  if(imm) { /*  immediate */
+    return bits(byte, 0, 16);
+  } else {
+    return eval_reg(bits(byte + 1, 0, 8));
+  }
+}
+
+/* Eval register or immediate data.
+   xBBB_BBBB, if immediate use all 7 bits for data else use
+   lower four bits for the general purpose register number. */
+/* Evaluates gprm or data depending on bit, data is in byte n */
+uint16_t eval_reg_or_data_2(int imm, int byte) {
+  if(imm) /* immediate */
+    return bits(byte, 1, 7);
+  else
+    return state->GPRM[bits(byte, 4, 4)];
+}
+
+
+/* Compare data using operation, return result from comparison. 
+   Helper function for the different if functions. */
+static bool eval_compare(uint8_t operation, uint16_t data1, uint16_t data2) {
+  switch(operation) {
+    case 1:
+      return data1 & data2;
+    case 2:
+      return data1 == data2;
+    case 3:
+      return data1 != data2;
+    case 4:
+      return data1 >= data2;
+    case 5:
+      return data1 >  data2;
+    case 6:
+      return data1 <= data2;
+    case 7:
+      return data1 <  data2;
+  }
+  fprintf(stderr,"eval_compare: Invalid comparison code\n");
+  return 0;
+}
+
+
+/* Evaluate if version 1.
+   Has comparison data in byte 3 and 4-5 (immediate or register) */
+static bool eval_if_version_1(void) {
+  uint8_t op = bits(1, 1, 3);
+  if(op) {
+    return eval_compare(op, eval_reg(bits(3, 0, 8)), 
+                            eval_reg_or_data(bits(1, 0, 1), 4));
+  }
+  return 1;
+}
+
+/* Evaluate if version 2.
+   This version only compares register which are in byte 6 and 7 */
+static bool eval_if_version_2(void) {
+  uint8_t op = bits(1, 1, 3);
+  if(op) {
+    return eval_compare(op, eval_reg(bits(6, 0, 8)), 
+                            eval_reg(bits(7, 0, 8)));
+  }
+  return 1;
+}
+
+/* Evaluate if version 3.
+   Has comparison data in byte 2 and 6-7 (immediate or register) */
+static bool eval_if_version_3(void) {
+  uint8_t op = bits(1, 1, 3);
+  if(op) {
+    return eval_compare(op, eval_reg(bits(2, 0, 8)), 
+                            eval_reg_or_data(bits(1, 0, 1), 6));
+  }
+  return 1;
+}
+
+/* Evaluate if version 4.
+   Has comparison data in byte 1 and 4-5 (immediate or register) 
+   The register in byte 1 is only the lowe nibble (4bits) */
+static bool eval_if_version_4(void) {
+  uint8_t op = bits(1, 1, 3);
+  if(op) {
+    return eval_compare(op, eval_reg(bits(1, 4, 4)), 
+                            eval_reg_or_data(bits(1, 0, 1), 4));
+  }
+  return 1;
+}
+
+/* Evaluate special instruction.... returns the new row/line number,
+   0 if no new row and 256 if Break. */
+static int eval_special_instruction(bool cond) {
+  int line, level;
+  
+  switch(bits(1, 4, 4)) {
+    case 0: /*  NOP */
+      line = 0;
+      return cond ? line : 0;
+    case 1: /*  Goto line */
+      line = bits(7, 0, 8);
+      return cond ? line : 0;
+    case 2: /*  Break */
+      /*  max number of rows < 256, so we will end this set */
+      line = 256;
+      return cond ? 256 : 0;
+    case 3: /*  Set temporary parental level and goto */
+      line = bits(7, 0, 8); 
+      level = bits(6, 4, 4);
+      if(cond) {
+	/*  This always succeeds now, if we want real parental protection */
+	/*  we need to ask the user and have passwords and stuff. */
+	state->SPRM[13] = level;
+      }
+      return cond ? line : 0;
+  }
+  return 0;
+}
+
+/* Evaluate link by subinstruction.
+   Return 1 if link, or 0 if no link
+   Actual link instruction is in return_values parameter */
+static bool eval_link_subins(bool cond, link_t *return_values) {
+  uint16_t button = bits(6, 0, 6);
+  uint8_t  linkop = bits(7, 3, 5);
+  
+  if(linkop > 0x10)
+    return 0;    /*  Unknown Link by Sub-Instruction command */
+
+  /*  Assumes that the link_cmd_t enum has the same values as the LinkSIns codes */
+  return_values->command = linkop;
+  return_values->data1 = button;
+  return cond;
+}
+
+
+/* Evaluate link instruction.
+   Return 1 if link, or 0 if no link
+   Actual link instruction is in return_values parameter */
+static bool eval_link_instruction(bool cond, link_t *return_values) {
+  uint8_t op = bits(1, 4, 4);
+  
+  switch(op) {
+    case 1:
+	return eval_link_subins(cond, return_values);
+    case 4:
+	return_values->command = LinkPGCN;
+	return_values->data1   = bits(6, 1, 15);
+	return cond;
+    case 5:
+	return_values->command = LinkPTTN;
+	return_values->data1 = bits(6, 6, 10);
+	return_values->data2 = bits(6, 0, 6);
+	return cond;
+    case 6:
+	return_values->command = LinkPGN;
+	return_values->data1 = bits(7, 1, 7);
+	return_values->data2 = bits(6, 0, 6);
+	return cond;
+    case 7:
+	return_values->command = LinkCN;
+	return_values->data1 = bits(7, 0, 8);
+	return_values->data2 = bits(6, 0, 6);
+	return cond;
+  }
+  return 0;
+}
+
+
+/* Evaluate a jump instruction.
+   returns 1 if jump or 0 if no jump
+   actual jump instruction is in return_values parameter */
+static bool eval_jump_instruction(bool cond, link_t *return_values) {
+  
+  switch(bits(1, 4, 4)) {
+    case 1:
+      return_values->command = Exit;
+      return cond;
+    case 2:
+      return_values->command = JumpTT;
+      return_values->data1 = bits(5, 1, 7);
+      return cond;
+    case 3:
+      return_values->command = JumpVTS_TT;
+      return_values->data1 = bits(5, 1, 7);
+      return cond;
+    case 5:
+      return_values->command = JumpVTS_PTT;
+      return_values->data1 = bits(5, 1, 7);
+      return_values->data2 = bits(2, 6, 10);
+      return cond;
+    case 6:
+      switch(bits(5,0,2)) {
+        case 0:
+          return_values->command = JumpSS_FP;
+          return cond;
+        case 1:
+          return_values->command = JumpSS_VMGM_MENU;
+          return_values->data1 =  bits(5, 4, 4);
+          return cond;
+        case 2:
+          return_values->command = JumpSS_VTSM;
+          return_values->data1 =  bits(4, 0, 8);
+          return_values->data2 =  bits(3, 0, 8);
+          return_values->data3 =  bits(5, 4, 4);
+          return cond;
+        case 3:
+          return_values->command = JumpSS_VMGM_PGC;
+          return_values->data1 =  bits(2, 1, 15);
+          return cond;
+        }
+      break;
+    case 8:
+      switch(bits(5,0,2)) {
+        case 0:
+          return_values->command = CallSS_FP;
+          return_values->data1 = bits(4, 0, 8);
+          return cond;
+        case 1:
+          return_values->command = CallSS_VMGM_MENU;
+          return_values->data1 = bits(5, 4, 4);
+          return_values->data2 = bits(4, 0 ,8);
+          return cond;
+        case 2:
+          return_values->command = CallSS_VTSM;
+          return_values->data1 = bits(5, 4, 4);
+          return_values->data2 = bits(4, 0, 8);
+          return cond;
+        case 3:
+          return_values->command = CallSS_VMGM_PGC;
+          return_values->data1 = bits(2, 1, 15);
+          return_values->data2 = bits(4, 0, 8);
+          return cond;
+      }
+      break;
+  }
+  return 0;
+}
+
+/* Evaluate a set sytem register instruction 
+   May contain a link so return the same as eval_link */
+static bool eval_system_set(int cond, link_t *return_values) {
+  int i;
+  uint16_t data, data2;
+  
+  switch(bits(0, 4, 4)) {
+    case 1: /*  Set system reg 1 &| 2 &| 3 (Audio, Subp. Angle) */
+      for(i = 1; i <= 3; i++) {
+        if(bits(2 + i, 0, 1)) {
+          data = eval_reg_or_data_2(bits(0, 3, 1), 2 + i);
+          if(cond) {
+            state->SPRM[i] = data;
+          }
+        }
+      }
+      break;
+    case 2: /*  Set system reg 9 & 10 (Navigation timer, Title PGC number) */
+      data = eval_reg_or_data(bits(0, 3, 1), 2);
+      data2 = bits(5, 0, 8); /*  ?? size */
+      if(cond) {
+	state->SPRM[9] = data; /*  time */
+	state->SPRM[10] = data2; /*  pgcN */
+      }
+      break;
+    case 3: /*  Mode: Counter / Register + Set */
+      data = eval_reg_or_data(bits(0, 3, 1), 2);
+      data2 = bits(5, 4, 4);
+      if(bits(5, 0, 1)) {
+	fprintf(stderr, "Detected SetGPRMMD Counter!! This is unsupported.\n");
+	/* exit(-1); */
+      } else {
+	;
+      }
+      if(cond) {
+	state->GPRM[data2] = data;
+      }
+      break;
+    case 6: /*  Set system reg 8 (Highlighted button) */
+      data = eval_reg_or_data(bits(0, 3, 1), 4); /*  Not system reg!! */
+      if(cond) {
+	state->SPRM[8] = data;
+      }
+      break;
+  }
+  if(bits(1, 4, 4)) {
+    return eval_link_instruction(cond, return_values);
+  }
+  return 0;
+}
+
+
+/* Evaluate set operation
+   Sets the register given to the value indicated by op and data.
+   For the swap case the contents of reg is stored in reg2.
+*/
+static void eval_set_op(int op, int reg, int reg2, int data) {
+  switch(op) {
+    case 1:
+      state->GPRM[reg] = data;
+      break;
+    case 2: /* SPECIAL CASE - SWAP! */
+      state->GPRM[reg2] = state->GPRM[reg];
+      state->GPRM[reg] = data;
+      break;
+    case 3:
+      state->GPRM[reg] += data;
+      break;
+    case 4:
+      state->GPRM[reg] -= data;
+      break;
+    case 5:
+      state->GPRM[reg] *= data;
+      break;
+    case 6:
+      state->GPRM[reg] /= data;
+      break;
+    case 7:
+      state->GPRM[reg] %= data;
+      break;
+    case 8: /* SPECIAL CASE - RND! */
+      state->GPRM[reg] += data; /*  TODO FIXME */
+      break;
+    case 9:
+      state->GPRM[reg] &= data;
+      break;
+    case 10:
+      state->GPRM[reg] |= data;
+      break;
+    case 11:
+      state->GPRM[reg] ^= data;
+      break;
+  }
+}
+
+/* Evaluate set instruction, combined with either Link or Compare. */
+static void eval_set_version_1(int cond) {
+  uint8_t  op   = bits(0, 4, 4);
+  uint8_t  reg  = bits(3, 4, 4); /*  Erhumm.. */
+  uint8_t  reg2 = bits(5, 4, 4);
+  uint16_t data = eval_reg_or_data(bits(0, 3, 1), 4);
+
+  if(cond) {
+    eval_set_op(op, reg, reg2, data);
+  }
+}
+
+
+/* Evaluate set instruction, combined with both Link and Compare. */
+static void eval_set_version_2(int cond) {
+  uint8_t  op   = bits(0, 4, 4);
+  uint8_t  reg  = bits(1, 4, 4);
+  uint8_t  reg2 = bits(3, 4, 4); /*  Erhumm.. */
+  uint16_t data = eval_reg_or_data(bits(0, 3, 1), 2);
+
+  if(cond) {
+    eval_set_op(op, reg, reg2, data);
+  }
+}
+
+
+/* Evaluate a command
+   returns row number of goto, 0 if no goto, -1 if link.
+   Link command in return_values */
+static int eval_command(uint8_t *bytes, link_t *return_values) {
+  int i, extra_bits;
+  int cond, res = 0;
+
+  for(i = 0; i < 8; i++) {
+    cmd.bits[i] = bytes[i];
+    cmd.examined[i] = 0;
+  }
+  memset(return_values, 0, sizeof(link_t));
+
+  switch(bits(0, 0, 3)) { /* three first bits */
+    case 0: /*  Special instructions */
+      cond = eval_if_version_1();
+      res = eval_special_instruction(cond);
+      if(res == -1) {
+	fprintf(stderr, "Unknown Instruction!\n");
+	/* exit(0); */
+      }
+      break;
+    case 1: /*  Link/jump instructions */
+      if(bits(0, 3, 1)) {
+        cond = eval_if_version_2();
+        res = eval_jump_instruction(cond, return_values);
+      } else {
+        cond = eval_if_version_1();
+        res = eval_link_instruction(cond, return_values);
+      }
+      if(res)
+	res = -1;
+      break;
+    case 2: /*  System set instructions */
+      cond = eval_if_version_2();
+      res = eval_system_set(cond, return_values);
+      if(res)
+	res = -1;
+      break;
+    case 3: /*  Set instructions, either Compare or Link may be used */
+      cond = eval_if_version_3();
+      eval_set_version_1(cond);
+      if(bits(1, 4, 4)) {
+	res = eval_link_instruction(cond, return_values);
+      }
+      if(res)
+	res = -1;
+      break;
+    case 4: /*  Set, Compare -> Link Sub-Instruction */
+      eval_set_version_2(/*True*/ 1);
+      cond = eval_if_version_4();
+      res = eval_link_subins(cond, return_values);
+      if(res)
+	res = -1;
+      break;
+    case 5: /*  Compare -> (Set and Link Sub-Instruction) */
+      cond = eval_if_version_4();
+      eval_set_version_2(cond);
+      res = eval_link_subins(cond, return_values);
+      if(res)
+	res = -1;
+      break;
+    case 6: /*  Compare -> Set, allways Link Sub-Instruction */
+      cond = eval_if_version_4();
+      eval_set_version_2(cond);
+      res = eval_link_subins(/*True*/ 1, return_values);
+      if(res)
+	res = -1;
+      break;
+  }
+  /*  Check if there are bits not yet examined */
+
+  extra_bits = 0;
+  for(i = 0; i < 8; i++)
+    if(cmd.bits [i] & ~cmd.examined [i]) {
+      extra_bits = 1;
+      break;
+    }
+  if(extra_bits) {
+    fprintf(stderr, "[WARNING, unknown bits:");
+    for(i = 0; i < 8; i++)
+      fprintf(stderr, " %02x", cmd.bits [i] & ~cmd.examined [i]);
+    fprintf(stderr, "]\n");
+  }
+
+  return res;
+}
+
+/* Evaluate a set of commands in the given register set (which is
+ * modified */
+int vmEval_CMD(vm_cmd_t commands[], int num_commands, 
+	       registers_t *registers, link_t *return_values) {
+  int i = 0;
+  int total = 0;
+  
+  state = registers; /*  TODO FIXME */
+
+#ifdef TRACE
+  /*  DEBUG */
+  if(1) {
+    int i;
+    fprintf(stderr, "   #   ");
+    for(i = 0; i < 24; i++)
+    fprintf(stderr, " %2d |", i);
+    fprintf(stderr, "\nSRPMS: ");
+    for(i = 0; i < 24; i++)
+      fprintf(stderr, "%04x|", state->SPRM[i]);
+    fprintf(stderr, "\nGRPMS: ");
+    for(i = 0; i < 16; i++)
+      fprintf(stderr, "%04x|", state->GPRM[i]);
+    fprintf(stderr, "\n");
+  }
+  if(1) {
+    int i;
+    for(i = 0; i < num_commands; i++)
+      vmPrint_CMD(i, &commands[i]);
+    fprintf(stderr, "--------------------------------------------\n");
+  } /*  end DEBUG */
+#endif
+  
+  while(i < num_commands && total < 100000) {
+    int line;
+    
+    if(0) vmPrint_CMD(i, &commands[i]);
+    line = eval_command(&commands[i].bytes[0], return_values);
+    
+    if (line < 0) { /*  Link command */
+      fprintf(stderr, "eval: Doing Link/Jump/Call\n"); 
+      return 1;
+    }
+    
+    if (line > 0) /*  Goto command */
+      i = line - 1;
+    else /*  Just continue on the next line */
+      i++;
+
+    total++;
+  }
+  
+  memset(return_values, 0, sizeof(link_t));
+  return 0;
+}
+
+static char *linkcmd2str(link_cmd_t cmd) {
+  switch(cmd) {
+  case LinkNoLink:
+    return "LinkNoLink";
+  case LinkTopC:
+    return "LinkTopC";
+  case LinkNextC:
+    return "LinkNextC";
+  case LinkPrevC:
+    return "LinkPrevC";
+  case LinkTopPG:
+    return "LinkTopPG";
+  case LinkNextPG:
+    return "LinkNextPG";
+  case LinkPrevPG:
+    return "LinkPrevPG";
+  case LinkTopPGC:
+    return "LinkTopPGC";
+  case LinkNextPGC:
+    return "LinkNextPGC";
+  case LinkPrevPGC:
+    return "LinkPrevPGC";
+  case LinkGoUpPGC:
+    return "LinkGoUpPGC";
+  case LinkTailPGC:
+    return "LinkTailPGC";
+  case LinkRSM:
+    return "LinkRSM";
+  case LinkPGCN:
+    return "LinkPGCN";
+  case LinkPTTN:
+    return "LinkPTTN";
+  case LinkPGN:
+    return "LinkPGN";
+  case LinkCN:
+    return "LinkCN";
+  case Exit:
+    return "Exit";
+  case JumpTT:
+    return "JumpTT";
+  case JumpVTS_TT:
+    return "JumpVTS_TT";
+  case JumpVTS_PTT:
+    return "JumpVTS_PTT";
+  case JumpSS_FP:
+    return "JumpSS_FP";
+  case JumpSS_VMGM_MENU:
+    return "JumpSS_VMGM_MENU";
+  case JumpSS_VTSM:
+    return "JumpSS_VTSM";
+  case JumpSS_VMGM_PGC:
+    return "JumpSS_VMGM_PGC";
+  case CallSS_FP:
+    return "CallSS_FP";
+  case CallSS_VMGM_MENU:
+    return "CallSS_VMGM_MENU";
+  case CallSS_VTSM:
+    return "CallSS_VTSM";
+  case CallSS_VMGM_PGC:
+    return "CallSS_VMGM_PGC";
+  case PlayThis:
+    return "PlayThis";
+  }
+  return "*** (bug)";
+}
+
+void vmPrint_LINK(link_t value) {
+  char *cmd = linkcmd2str(value.command);
+    
+  switch(value.command) {
+  case LinkNoLink:
+  case LinkTopC:
+  case LinkNextC:
+  case LinkPrevC:
+  case LinkTopPG:
+  case LinkNextPG:
+  case LinkPrevPG:
+  case LinkTopPGC:
+  case LinkNextPGC:
+  case LinkPrevPGC:
+  case LinkGoUpPGC:
+  case LinkTailPGC:
+  case LinkRSM:
+    fprintf(stderr, "%s (button %d)\n", cmd, value.data1);
+    break;
+  case LinkPGCN:
+  case JumpTT:
+  case JumpVTS_TT:
+  case JumpSS_VMGM_MENU: /*  == 2 -> Title Menu */
+  case JumpSS_VMGM_PGC:
+    fprintf(stderr, "%s %d\n", cmd, value.data1);
+    break;
+  case LinkPTTN:
+  case LinkPGN:
+  case LinkCN:
+    fprintf(stderr, "%s %d (button %d)\n", cmd, value.data1, value.data2);
+    break;
+  case Exit:
+  case JumpSS_FP:
+  case PlayThis: /*  Humm.. should we have this at all.. */
+    fprintf(stderr, "%s\n", cmd);
+    break;
+  case JumpVTS_PTT:
+    fprintf(stderr, "%s %d:%d\n", cmd, value.data1, value.data2);
+    break;
+  case JumpSS_VTSM:
+    fprintf(stderr, "%s vts %d title %d menu %d\n", 
+	    cmd, value.data1, value.data2, value.data3);
+    break;
+  case CallSS_FP:
+    fprintf(stderr, "%s resume cell %d\n", cmd, value.data1);
+    break;
+  case CallSS_VMGM_MENU: /*  == 2 -> Title Menu */
+  case CallSS_VTSM:
+    fprintf(stderr, "%s %d resume cell %d\n", cmd, value.data1, value.data2);
+    break;
+  case CallSS_VMGM_PGC:
+    fprintf(stderr, "%s %d resume cell %d\n", cmd, value.data1, value.data2);
+    break;
+  }
+ }