/***
 * CopyPolicy: GNU Public License 2 applies
 * Copyright (C) by Monty (xiphmont@mit.edu)
 *
 * Gapa analysis support code for paranoia
 *
 ***/

#include <string.h>
#include "p_block.h"
#include "cdda_paranoia.h"
#include "gap.h"

/**** Gap analysis code ***************************************************/

long i_paranoia_overlap_r(int16_t *buffA,int16_t *buffB,
			  long offsetA, long offsetB){
  long beginA=offsetA;
  long beginB=offsetB;

  for(;beginA>=0 && beginB>=0;beginA--,beginB--)
    if(buffA[beginA]!=buffB[beginB])break;
  beginA++;
  beginB++;
  
  return(offsetA-beginA);
}

long i_paranoia_overlap_f(int16_t *buffA,int16_t *buffB,
			  long offsetA, long offsetB,
			  long sizeA,long sizeB){
  long endA=offsetA;
  long endB=offsetB;
  
  for(;endA<sizeA && endB<sizeB;endA++,endB++)
    if(buffA[endA]!=buffB[endB])break;
  
  return(endA-offsetA);
}

int i_stutter_or_gap(int16_t *A, int16_t *B,long offA, long offB,
		     long gap){
  long a1=offA;
  long b1=offB;
  
  if(a1<0){
    b1-=a1;
    gap+=a1;
    a1=0;
  }
  
  return(memcmp(A+a1,B+b1,gap*2));
}

/* riftv is the first value into the rift -> or <- */
void i_analyze_rift_f(int16_t *A,int16_t *B,
		      long sizeA, long sizeB,
		      long aoffset, long boffset, 
		      long *matchA,long *matchB,long *matchC){
  
  long apast=sizeA-aoffset;
  long bpast=sizeB-boffset;
  long i;
  
  *matchA=0, *matchB=0, *matchC=0;
  
  /* Look for three possible matches... (A) Ariftv->B, (B) Briftv->A and 
     (c) AB->AB. */
  
  for(i=0;;i++){
    if(i<bpast) /* A */
      if(i_paranoia_overlap_f(A,B,aoffset,boffset+i,sizeA,sizeB)>=MIN_WORDS_RIFT){
	*matchA=i;
	break;
      }
    
    if(i<apast){ /* B */
      if(i_paranoia_overlap_f(A,B,aoffset+i,boffset,sizeA,sizeB)>=MIN_WORDS_RIFT){
	*matchB=i;
	break;
      }
      if(i<bpast) /* C */
	if(i_paranoia_overlap_f(A,B,aoffset+i,boffset+i,sizeA,sizeB)>=MIN_WORDS_RIFT){
	  *matchC=i;
	  break;
	}
    }else
      if(i>=bpast)break;
    
  }
  
  if(*matchA==0 && *matchB==0 && *matchC==0)return;
  
  if(*matchC)return;
  if(*matchA){
    if(i_stutter_or_gap(A,B,aoffset-*matchA,boffset,*matchA))
      return;
    *matchB=-*matchA; /* signify we need to remove n bytes from B */
    *matchA=0;
    return;
  }else{
    if(i_stutter_or_gap(B,A,boffset-*matchB,aoffset,*matchB))
      return;
    *matchA=-*matchB;
    *matchB=0;
    return;
  }
}

/* riftv must be first even val of rift moving back */

void i_analyze_rift_r(int16_t *A,int16_t *B,
		      long sizeA, long sizeB,
		      long aoffset, long boffset, 
		      long *matchA,long *matchB,long *matchC){
  
  long apast=aoffset+1;
  long bpast=boffset+1;
  long i;
  
  *matchA=0, *matchB=0, *matchC=0;
  
  /* Look for three possible matches... (A) Ariftv->B, (B) Briftv->A and 
     (c) AB->AB. */
  
  for(i=0;;i++){
    if(i<bpast) /* A */
      if(i_paranoia_overlap_r(A,B,aoffset,boffset-i)>=MIN_WORDS_RIFT){
	*matchA=i;
	break;
      }
    if(i<apast){ /* B */
      if(i_paranoia_overlap_r(A,B,aoffset-i,boffset)>=MIN_WORDS_RIFT){
	*matchB=i;
	break;
      }      
      if(i<bpast) /* C */
	if(i_paranoia_overlap_r(A,B,aoffset-i,boffset-i)>=MIN_WORDS_RIFT){
	  *matchC=i;
	  break;
	}
    }else
      if(i>=bpast)break;
    
  }
  
  if(*matchA==0 && *matchB==0 && *matchC==0)return;
  
  if(*matchC)return;
  
  if(*matchA){
    if(i_stutter_or_gap(A,B,aoffset+1,boffset-*matchA+1,*matchA))
      return;
    *matchB=-*matchA; /* signify we need to remove n bytes from B */
    *matchA=0;
    return;
  }else{
    if(i_stutter_or_gap(B,A,boffset+1,aoffset-*matchB+1,*matchB))
      return;
    *matchA=-*matchB;
    *matchB=0;
    return;
  }
}

void  analyze_rift_silence_f(int16_t *A,int16_t *B,long sizeA,long sizeB,
			     long aoffset, long boffset,
			     long *matchA, long *matchB){
  *matchA=-1;
  *matchB=-1;

  sizeA=prna_min(sizeA,aoffset+MIN_WORDS_RIFT);
  sizeB=prna_min(sizeB,boffset+MIN_WORDS_RIFT);

  aoffset++;
  boffset++;

  while(aoffset<sizeA){
    if(A[aoffset]!=A[aoffset-1]){
      *matchA=0;
      break;
    }
    aoffset++;
  }

  while(boffset<sizeB){
    if(B[boffset]!=B[boffset-1]){
      *matchB=0;
      break;
    }
    boffset++;
  }
}