decoder.c

linux下的MPEG1

/*
 * Copyright (C) 2000, 2001 Martin Norbäck, Håkan Hjort
 *               2002-2004 the dvdnav project
 * 
 * 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: decoder.c,v 1.14 2004/03/16 11:43:38 mroi Exp $
 *
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdio.h>
#include <stdlib.h>
#include <inttypes.h>
#include <string.h>  /* For memset */
#include "ifo_types.h" /* vm_cmd_t */

#include "dvdnav_internal.h"

uint32_t vm_getbits(command_t *command, int32_t start, int32_t count) {
  uint64_t result = 0;
  uint64_t bit_mask = 0;
  uint64_t examining = 0;
  int32_t  bits;
  
  if (count == 0) return 0;

  if ( ((start - count) < -1) ||
       (count > 32) ||
       (start > 63) ||
       (count < 0) ||
       (start < 0) ) {
    fprintf(MSG_OUT, "libdvdnav: Bad call to vm_getbits. Parameter out of range\n");
    abort();
  }
  /* all ones, please */
  bit_mask = ~bit_mask;
  bit_mask >>= 63 - start;
  bits = start + 1 - count;
  examining = ((bit_mask >> bits) << bits );
  command->examined |= examining;
  result = (command->instruction & bit_mask) >> bits;
  return (uint32_t) result;
}

static uint16_t get_GPRM(registers_t* registers, uint8_t reg) {
  if (registers->GPRM_mode[reg] & 0x01) {
    struct timeval current_time, time_offset;
    uint16_t result;
    /* Counter mode */
    /* fprintf(MSG_OUT, "libdvdnav: Getting counter %d\n",reg);*/
    gettimeofday(&current_time, NULL);
    time_offset.tv_sec = current_time.tv_sec - registers->GPRM_time[reg].tv_sec;
    time_offset.tv_usec = current_time.tv_usec - registers->GPRM_time[reg].tv_usec;
    if (time_offset.tv_usec < 0) { 
      time_offset.tv_sec--; 
      time_offset.tv_usec += 1000000;
    }
    result = (uint16_t) (time_offset.tv_sec & 0xffff);
    registers->GPRM[reg]=result;
    return result; 

  } else {
    /* Register mode */
    return registers->GPRM[reg];
  }
  
}

static void set_GPRM(registers_t* registers, uint8_t reg, uint16_t value) {
  if (registers->GPRM_mode[reg] & 0x01) {
    struct timeval current_time;
    /* Counter mode */
    /* fprintf(MSG_OUT, "libdvdnav: Setting counter %d\n",reg); */
    gettimeofday(&current_time, NULL);
    registers->GPRM_time[reg] = current_time;
    registers->GPRM_time[reg].tv_sec -= value;
  }
  registers->GPRM[reg] = value;
}

/* 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(command_t* command, uint8_t reg) {
  if(reg & 0x80) {
    if ((reg & 0x1f) == 20) {
      fprintf(MSG_OUT, "libdvdnav: Suspected RCE Region Protection!!!\n");
    }
    return command->registers->SPRM[reg & 0x1f]; /*  FIXME max 24 not 32 */
  } else {
    return get_GPRM(command->registers, 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(command_t* command, int32_t imm, int32_t start) {
  if(imm) { /*  immediate */
    return vm_getbits(command, start, 16);
  } else {
    return eval_reg(command, vm_getbits(command, (start - 8), 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 */
static uint16_t eval_reg_or_data_2(command_t* command, 
				   int32_t imm, int32_t start) {
  if(imm) /* immediate */
    return vm_getbits(command, (start - 1), 7);
  else
    return get_GPRM(command->registers, (vm_getbits(command, (start - 4), 4)) );
}


/* Compare data using operation, return result from comparison. 
   Helper function for the different if functions. */
static int32_t 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(MSG_OUT, "libdvdnav: 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 int32_t eval_if_version_1(command_t* command) {
  uint8_t op = vm_getbits(command, 54, 3);
  if(op) {
    return eval_compare(op, eval_reg(command, vm_getbits(command, 39, 8)), 
                            eval_reg_or_data(command, vm_getbits(command, 55, 1), 31));
  }
  return 1;
}

/* Evaluate if version 2.
   This version only compares register which are in byte 6 and 7 */
static int32_t eval_if_version_2(command_t* command) {
  uint8_t op = vm_getbits(command, 54, 3);
  if(op) {
    return eval_compare(op, eval_reg(command, vm_getbits(command, 15, 8)), 
                            eval_reg(command, vm_getbits(command, 7, 8)));
  }
  return 1;
}

/* Evaluate if version 3.
   Has comparison data in byte 2 and 6-7 (immediate or register) */
static int32_t eval_if_version_3(command_t* command) {
  uint8_t op = vm_getbits(command, 54, 3);
  if(op) {
    return eval_compare(op, eval_reg(command, vm_getbits(command, 47, 8)), 
                            eval_reg_or_data(command, vm_getbits(command, 55, 1), 15));
  }
  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 (4 bits) */
static int32_t eval_if_version_4(command_t* command) {
  uint8_t op = vm_getbits(command, 54, 3);
  if(op) {
    return eval_compare(op, eval_reg(command, vm_getbits(command, 51, 4)), 
                            eval_reg_or_data(command, vm_getbits(command, 55, 1), 31));
  }
  return 1;
}

/* Evaluate special instruction.... returns the new row/line number,
   0 if no new row and 256 if Break. */
static int32_t eval_special_instruction(command_t* command, int32_t cond) {
  int32_t line, level;
  
  switch(vm_getbits(command, 51, 4)) {
    case 0: /*  NOP */
      line = 0;
      return cond ? line : 0;
    case 1: /*  Goto line */
      line = vm_getbits(command, 7, 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 = vm_getbits(command, 7, 8); 
      level = vm_getbits(command, 11, 4);
      if(cond) {
	/*  This always succeeds now, if we want real parental protection */
	/*  we need to ask the user and have passwords and stuff. */
	command->registers->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 int32_t eval_link_subins(command_t* command, int32_t cond, link_t *return_values) {
  uint16_t button = vm_getbits(command, 15, 6);
  uint8_t  linkop = vm_getbits(command, 4, 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 int32_t eval_link_instruction(command_t* command, int32_t cond, link_t *return_values) {
  uint8_t op = vm_getbits(command, 51, 4);
  
  switch(op) {
    case 1:
	return eval_link_subins(command, cond, return_values);
    case 4:
	return_values->command = LinkPGCN;
	return_values->data1   = vm_getbits(command, 14, 15);
	return cond;
    case 5:
	return_values->command = LinkPTTN;
	return_values->data1 = vm_getbits(command, 9, 10);
	return_values->data2 = vm_getbits(command, 15, 6);
	return cond;
    case 6:
	return_values->command = LinkPGN;
	return_values->data1 = vm_getbits(command, 6, 7);
	return_values->data2 = vm_getbits(command, 15, 6);
	return cond;
    case 7:
	return_values->command = LinkCN;
	return_values->data1 = vm_getbits(command, 7, 8);
	return_values->data2 = vm_getbits(command, 15, 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 int32_t eval_jump_instruction(command_t* command, int32_t cond, link_t *return_values) {
  
  switch(vm_getbits(command, 51, 4)) {
    case 1:
      return_values->command = Exit;
      return cond;
    case 2:
      return_values->command = JumpTT;
      return_values->data1 = vm_getbits(command, 22, 7);
      return cond;
    case 3:
      return_values->command = JumpVTS_TT;
      return_values->data1 = vm_getbits(command, 22, 7);
      return cond;
    case 5:
      return_values->command = JumpVTS_PTT;
      return_values->data1 = vm_getbits(command, 22, 7);
      return_values->data2 = vm_getbits(command, 41, 10);
      return cond;
    case 6:
      switch(vm_getbits(command, 23, 2)) {
        case 0:
          return_values->command = JumpSS_FP;
          return cond;
        case 1:
          return_values->command = JumpSS_VMGM_MENU;
          return_values->data1 =  vm_getbits(command, 19, 4);
          return cond;
        case 2:
          return_values->command = JumpSS_VTSM;
          return_values->data1 =  vm_getbits(command, 31, 8);
          return_values->data2 =  vm_getbits(command, 39, 8);
          return_values->data3 =  vm_getbits(command, 19, 4);
          return cond;
        case 3:
          return_values->command = JumpSS_VMGM_PGC;
          return_values->data1 =  vm_getbits(command, 46, 15);
          return cond;
        }
      break;
    case 8:
      switch(vm_getbits(command, 23, 2)) {
        case 0:
          return_values->command = CallSS_FP;
          return_values->data1 = vm_getbits(command, 31, 8);
          return cond;
        case 1:
          return_values->command = CallSS_VMGM_MENU;
          return_values->data1 = vm_getbits(command, 19, 4);
          return_values->data2 = vm_getbits(command, 31, 8);
          return cond;
        case 2:
          return_values->command = CallSS_VTSM;
          return_values->data1 = vm_getbits(command, 19, 4);
          return_values->data2 = vm_getbits(command, 31, 8);
          return cond;
        case 3:
          return_values->command = CallSS_VMGM_PGC;
          return_values->data1 = vm_getbits(command, 46, 15);
          return_values->data2 = vm_getbits(command, 31, 8);
          return cond;
      }
      break;
  }
  return 0;
}

/* Evaluate a set sytem register instruction 
   May contain a link so return the same as eval_link */
static int32_t eval_system_set(command_t* command, int32_t cond, link_t *return_values) {
  int32_t i;
  uint16_t data, data2;
  
  switch(vm_getbits(command, 59, 4)) {
    case 1: /*  Set system reg 1 &| 2 &| 3 (Audio, Subp. Angle) */
      for(i = 1; i <= 3; i++) {
        if(vm_getbits(command, 63 - ((2 + i)*8), 1)) {
          data = eval_reg_or_data_2(command, vm_getbits(command, 60, 1), (47 - (i*8)));
          if(cond) {
            command->registers->SPRM[i] = data;
          }
        }
      }
      break;
    case 2: /*  Set system reg 9 & 10 (Navigation timer, Title PGC number) */
      data = eval_reg_or_data(command, vm_getbits(command, 60, 1), 47);
      data2 = vm_getbits(command, 23, 8); /*  ?? size */
      if(cond) {
	command->registers->SPRM[9] = data; /*  time */
	command->registers->SPRM[10] = data2; /*  pgcN */
      }
      break;
    case 3: /*  Mode: Counter / Register + Set */
      data = eval_reg_or_data(command, vm_getbits(command, 60, 1), 47);
      data2 = vm_getbits(command, 19, 4);
      if(vm_getbits(command, 23, 1)) {
	command->registers->GPRM_mode[data2] |= 1; /* Set bit 0 */
      } else {
	command->registers->GPRM_mode[data2] &= ~ 0x01; /* Reset bit 0 */
      }
      if(cond) {
        set_GPRM(command->registers, data2, data);
      }