/*
	Licensed to the Apache Software Foundation (ASF) under one
	or more contributor license agreements.  See the NOTICE file
	distributed with this work for additional information
	regarding copyright ownership.  The ASF licenses this file
	to you under the Apache License, Version 2.0 (the
	"License"); you may not use this file except in compliance
	with the License.  You may obtain a copy of the License at

	  http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing,
	software distributed under the License is distributed on an
	"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	KIND, either express or implied.  See the License for the
	specific language governing permissions and limitations
	under the License.
*/

/* AMCL basic functions for BIG type */
/* SU=m, SU is Stack Usage */

#include "big_256_56.h"

/* test a=0? */
int BIG_256_56_iszilch(BIG_256_56 a)
{
    int i;
    for (i=0; i<NLEN_256_56; i++)
        if (a[i]!=0) return 0;
    return 1;
}

/* test a=1? */
int BIG_256_56_isunity(BIG_256_56 a)
{
    int i;
    for(i=1; i<NLEN_256_56; i++)
        if (a[i]!=0) return 0;
    if (a[0]!=1) return 0;
    return 1;
}

/* test a=0? */
int BIG_256_56_diszilch(DBIG_256_56 a)
{
    int i;
    for (i=0; i<DNLEN_256_56; i++)
        if (a[i]!=0) return 0;
    return 1;
}

/* SU= 56 */
/* output a */
void BIG_256_56_output(BIG_256_56 a)
{
    BIG_256_56 b;
    int i,len;
    len=BIG_256_56_nbits(a);
    if (len%4==0) len/=4;
    else
    {
        len/=4;
        len++;
    }
    if (len<MODBYTES_256_56*2) len=MODBYTES_256_56*2;

    for (i=len-1; i>=0; i--)
    {
        BIG_256_56_copy(b,a);
        BIG_256_56_shr(b,i*4);
        printf("%01x",(unsigned int) b[0]&15);
    }
}

/* SU= 16 */
void BIG_256_56_rawoutput(BIG_256_56 a)
{
    int i;
    printf("(");
    for (i=0; i<NLEN_256_56-1; i++)
#if CHUNK==64
        printf("%"PRIxMAX",",(uintmax_t) a[i]);
    printf("%"PRIxMAX")",(uintmax_t) a[NLEN_256_56-1]);
#else
        printf("%x,",(unsigned int) a[i]);
    printf("%x)",(unsigned int) a[NLEN_256_56-1]);
#endif
}

/* Swap a and b if d=1 */
void BIG_256_56_cswap(BIG_256_56 a,BIG_256_56 b,int d)
{
    int i;
    chunk t,c=d;
    c=~(c-1);
#ifdef DEBUG_NORM
    for (i=0; i<NLEN_256_56+2; i++)
#else
    for (i=0; i<NLEN_256_56; i++)
#endif
    {
        t=c&(a[i]^b[i]);
        a[i]^=t;
        b[i]^=t;
    }
}

/* Move b to a if d=1 */
void BIG_256_56_cmove(BIG_256_56 f,BIG_256_56 g,int d)
{
    int i;
    chunk b=(chunk)-d;
#ifdef DEBUG_NORM
    for (i=0; i<NLEN_256_56+2; i++)
#else
    for (i=0; i<NLEN_256_56; i++)
#endif
    {
        f[i]^=(f[i]^g[i])&b;
    }
}

/* Move g to f if d=1 */
void BIG_256_56_dcmove(DBIG_256_56 f,DBIG_256_56 g,int d)
{
    int i;
    chunk b=(chunk)-d;
#ifdef DEBUG_NORM
    for (i=0; i<DNLEN_256_56+2; i++)
#else
    for (i=0; i<DNLEN_256_56; i++)
#endif
    {
        f[i]^=(f[i]^g[i])&b;
    }
}

/* convert BIG to/from bytes */
/* SU= 64 */
void BIG_256_56_toBytes(char *b,BIG_256_56 a)
{
    int i;
    BIG_256_56 c;
    BIG_256_56_norm(a);
    BIG_256_56_copy(c,a);
    for (i=MODBYTES_256_56-1; i>=0; i--)
    {
        b[i]=c[0]&0xff;
        BIG_256_56_fshr(c,8);
    }
}

/* SU= 16 */
void BIG_256_56_fromBytes(BIG_256_56 a,char *b)
{
    int i;
    BIG_256_56_zero(a);
    for (i=0; i<MODBYTES_256_56; i++)
    {
        BIG_256_56_fshl(a,8);
        a[0]+=(int)(unsigned char)b[i];
        //BIG_256_56_inc(a,(int)(unsigned char)b[i]); BIG_256_56_norm(a);
    }
#ifdef DEBUG_NORM
    a[MPV_256_56]=1;
    a[MNV_256_56]=0;
#endif
}

void BIG_256_56_fromBytesLen(BIG_256_56 a,char *b,int s)
{
    int i,len=s;
    BIG_256_56_zero(a);

    if (len>MODBYTES_256_56) len=MODBYTES_256_56;
    for (i=0; i<len; i++)
    {
        BIG_256_56_fshl(a,8);
        a[0]+=(int)(unsigned char)b[i];
    }
#ifdef DEBUG_NORM
    a[MPV_256_56]=1;
    a[MNV_256_56]=0;
#endif
}



/* SU= 88 */
void BIG_256_56_doutput(DBIG_256_56 a)
{
    DBIG_256_56 b;
    int i,len;
    BIG_256_56_dnorm(a);
    len=BIG_256_56_dnbits(a);
    if (len%4==0) len/=4;
    else
    {
        len/=4;
        len++;
    }

    for (i=len-1; i>=0; i--)
    {
        BIG_256_56_dcopy(b,a);
        BIG_256_56_dshr(b,i*4);
        printf("%01x",(unsigned int) b[0]&15);
    }
}


void BIG_256_56_drawoutput(DBIG_256_56 a)
{
    int i;
    printf("(");
    for (i=0; i<DNLEN_256_56-1; i++)
#if CHUNK==64
        printf("%"PRIxMAX",",(uintmax_t) a[i]);
    printf("%"PRIxMAX")",(uintmax_t) a[DNLEN_256_56-1]);
#else
        printf("%x,",(unsigned int) a[i]);
    printf("%x)",(unsigned int) a[DNLEN_256_56-1]);
#endif
}

/* Copy b=a */
void BIG_256_56_copy(BIG_256_56 b,BIG_256_56 a)
{
    int i;
    for (i=0; i<NLEN_256_56; i++)
        b[i]=a[i];
#ifdef DEBUG_NORM
    b[MPV_256_56]=a[MPV_256_56];
    b[MNV_256_56]=a[MNV_256_56];
#endif
}

/* Copy from ROM b=a */
void BIG_256_56_rcopy(BIG_256_56 b,const BIG_256_56 a)
{
    int i;
    for (i=0; i<NLEN_256_56; i++)
        b[i]=a[i];
#ifdef DEBUG_NORM
    b[MPV_256_56]=1;
    b[MNV_256_56]=0;
#endif
}

/* double length DBIG copy b=a */
void BIG_256_56_dcopy(DBIG_256_56 b,DBIG_256_56 a)
{
    int i;
    for (i=0; i<DNLEN_256_56; i++)
        b[i]=a[i];
#ifdef DEBUG_NORM
    b[DMPV_256_56]=a[DMPV_256_56];
    b[DMNV_256_56]=a[DMNV_256_56];
#endif
}

/* Copy BIG to bottom half of DBIG */
void BIG_256_56_dscopy(DBIG_256_56 b,BIG_256_56 a)
{
    int i;
    for (i=0; i<NLEN_256_56-1; i++)
        b[i]=a[i];

    b[NLEN_256_56-1]=a[NLEN_256_56-1]&BMASK_256_56; /* top word normalized */
    b[NLEN_256_56]=a[NLEN_256_56-1]>>BASEBITS_256_56;

    for (i=NLEN_256_56+1; i<DNLEN_256_56; i++) b[i]=0;
#ifdef DEBUG_NORM
    b[DMPV_256_56]=a[MPV_256_56];
    b[DMNV_256_56]=a[MNV_256_56];
#endif
}

/* Copy BIG to top half of DBIG */
void BIG_256_56_dsucopy(DBIG_256_56 b,BIG_256_56 a)
{
    int i;
    for (i=0; i<NLEN_256_56; i++)
        b[i]=0;
    for (i=NLEN_256_56; i<DNLEN_256_56; i++)
        b[i]=a[i-NLEN_256_56];
#ifdef DEBUG_NORM
    b[DMPV_256_56]=a[MPV_256_56];
    b[DMNV_256_56]=a[MNV_256_56];
#endif
}

/* Copy bottom half of DBIG to BIG */
void BIG_256_56_sdcopy(BIG_256_56 b,DBIG_256_56 a)
{
    int i;
    for (i=0; i<NLEN_256_56; i++)
        b[i]=a[i];
#ifdef DEBUG_NORM
    b[MPV_256_56]=a[DMPV_256_56];
    b[MNV_256_56]=a[DMNV_256_56];
#endif
}

/* Copy top half of DBIG to BIG */
void BIG_256_56_sducopy(BIG_256_56 b,DBIG_256_56 a)
{
    int i;
    for (i=0; i<NLEN_256_56; i++)
        b[i]=a[i+NLEN_256_56];
#ifdef DEBUG_NORM
    b[MPV_256_56]=a[DMPV_256_56];
    b[MNV_256_56]=a[DMNV_256_56];

#endif
}

/* Set a=0 */
void BIG_256_56_zero(BIG_256_56 a)
{
    int i;
    for (i=0; i<NLEN_256_56; i++)
        a[i]=0;
#ifdef DEBUG_NORM
    a[MPV_256_56]=a[MNV_256_56]=0;
#endif
}

void BIG_256_56_dzero(DBIG_256_56 a)
{
    int i;
    for (i=0; i<DNLEN_256_56; i++)
        a[i]=0;
#ifdef DEBUG_NORM
    a[DMPV_256_56]=a[DMNV_256_56]=0;
#endif
}

/* set a=1 */
void BIG_256_56_one(BIG_256_56 a)
{
    int i;
    a[0]=1;
    for (i=1; i<NLEN_256_56; i++)
        a[i]=0;
#ifdef DEBUG_NORM
    a[MPV_256_56]=1;
    a[MNV_256_56]=0;
#endif
}



/* Set c=a+b */
/* SU= 8 */
void BIG_256_56_add(BIG_256_56 c,BIG_256_56 a,BIG_256_56 b)
{
    int i;
    for (i=0; i<NLEN_256_56; i++)
        c[i]=a[i]+b[i];
#ifdef DEBUG_NORM
    c[MPV_256_56]=a[MPV_256_56]+b[MPV_256_56];
    c[MNV_256_56]=a[MNV_256_56]+b[MNV_256_56];
    if (c[MPV_256_56]>NEXCESS_256_56)  printf("add problem - positive digit overflow %d\n",c[MPV_256_56]);
    if (c[MNV_256_56]>NEXCESS_256_56)  printf("add problem - negative digit overflow %d\n",c[MNV_256_56]);

#endif
}

/* Set c=c+d */
void BIG_256_56_inc(BIG_256_56 c,int d)
{
    BIG_256_56_norm(c);
    c[0]+=(chunk)d;
#ifdef DEBUG_NORM
    c[MPV_256_56]+=1;
#endif
}

/* Set c=a-b */
/* SU= 8 */
void BIG_256_56_sub(BIG_256_56 c,BIG_256_56 a,BIG_256_56 b)
{
    int i;
    for (i=0; i<NLEN_256_56; i++)
        c[i]=a[i]-b[i];
#ifdef DEBUG_NORM
    c[MPV_256_56]=a[MPV_256_56]+b[MNV_256_56];
    c[MNV_256_56]=a[MNV_256_56]+b[MPV_256_56];
    if (c[MPV_256_56]>NEXCESS_256_56)  printf("sub problem - positive digit overflow %d\n",c[MPV_256_56]);
    if (c[MNV_256_56]>NEXCESS_256_56)  printf("sub problem - negative digit overflow %d\n",c[MNV_256_56]);

#endif
}

/* SU= 8 */

void BIG_256_56_dsub(DBIG_256_56 c,DBIG_256_56 a,DBIG_256_56 b)
{
    int i;
    for (i=0; i<DNLEN_256_56; i++)
        c[i]=a[i]-b[i];
#ifdef DEBUG_NORM
    c[DMPV_256_56]=a[DMPV_256_56]+b[DMNV_256_56];
    c[DMNV_256_56]=a[DMNV_256_56]+b[DMPV_256_56];
    if (c[DMPV_256_56]>NEXCESS_256_56)  printf("double sub problem - positive digit overflow %d\n",c[DMPV_256_56]);
    if (c[DMNV_256_56]>NEXCESS_256_56)  printf("double sub problem - negative digit overflow %d\n",c[DMNV_256_56]);
#endif
}

void BIG_256_56_dadd(DBIG_256_56 c,DBIG_256_56 a,DBIG_256_56 b)
{
    int i;
    for (i=0; i<DNLEN_256_56; i++)
        c[i]=a[i]+b[i];
#ifdef DEBUG_NORM
    c[DMPV_256_56]=a[DMPV_256_56]+b[DMNV_256_56];
    c[DMNV_256_56]=a[DMNV_256_56]+b[DMPV_256_56];
    if (c[DMPV_256_56]>NEXCESS_256_56)  printf("double add problem - positive digit overflow %d\n",c[DMPV_256_56]);
    if (c[DMNV_256_56]>NEXCESS_256_56)  printf("double add problem - negative digit overflow %d\n",c[DMNV_256_56]);
#endif
}

/* Set c=c-1 */
void BIG_256_56_dec(BIG_256_56 c,int d)
{
    BIG_256_56_norm(c);
    c[0]-=(chunk)d;
#ifdef DEBUG_NORM
    c[MNV_256_56]+=1;
#endif
}

/* multiplication r=a*c by c<=NEXCESS_256_56 */
void BIG_256_56_imul(BIG_256_56 r,BIG_256_56 a,int c)
{
    int i;
    for (i=0; i<NLEN_256_56; i++) r[i]=a[i]*c;
#ifdef DEBUG_NORM
    r[MPV_256_56]=a[MPV_256_56]*c;
    r[MNV_256_56]=a[MNV_256_56]*c;
    if (r[MPV_256_56]>NEXCESS_256_56)  printf("int mul problem - positive digit overflow %d\n",r[MPV_256_56]);
    if (r[MNV_256_56]>NEXCESS_256_56)  printf("int mul problem - negative digit overflow %d\n",r[MNV_256_56]);

#endif
}

/* multiplication r=a*c by larger integer - c<=FEXCESS */
/* SU= 24 */
chunk BIG_256_56_pmul(BIG_256_56 r,BIG_256_56 a,int c)
{
    int i;
    chunk ak,carry=0;
//    BIG_256_56_norm(a);
    for (i=0; i<NLEN_256_56; i++)
    {
        ak=a[i];
        r[i]=0;
        carry=muladd_256_56(ak,(chunk)c,carry,&r[i]);
    }
#ifdef DEBUG_NORM
    r[MPV_256_56]=1;
    r[MNV_256_56]=0;
#endif
    return carry;
}

/* r/=3 */
/* SU= 16 */
int BIG_256_56_div3(BIG_256_56 r)
{
    int i;
    chunk ak,base,carry=0;
    BIG_256_56_norm(r);
    base=((chunk)1<<BASEBITS_256_56);
    for (i=NLEN_256_56-1; i>=0; i--)
    {
        ak=(carry*base+r[i]);
        r[i]=ak/3;
        carry=ak%3;
    }
    return (int)carry;
}

/* multiplication c=a*b by even larger integer b>FEXCESS, resulting in DBIG */
/* SU= 24 */
void BIG_256_56_pxmul(DBIG_256_56 c,BIG_256_56 a,int b)
{
    int j;
    chunk carry;
    BIG_256_56_dzero(c);
    carry=0;
    for (j=0; j<NLEN_256_56; j++)
        carry=muladd_256_56(a[j],(chunk)b,carry,&c[j]);
    c[NLEN_256_56]=carry;
#ifdef DEBUG_NORM
    c[DMPV_256_56]=1;
    c[DMNV_256_56]=0;
#endif
}

/* .. if you know the result will fit in a BIG, c must be distinct from a and b */
/* SU= 40 */
void BIG_256_56_smul(BIG_256_56 c,BIG_256_56 a,BIG_256_56 b)
{
    int i,j;
    chunk carry;
//    BIG_256_56_norm(a);
//    BIG_256_56_norm(b);

    BIG_256_56_zero(c);
    for (i=0; i<NLEN_256_56; i++)
    {
        carry=0;
        for (j=0; j<NLEN_256_56; j++)
        {
            if (i+j<NLEN_256_56)
                carry=muladd_256_56(a[i],b[j],carry,&c[i+j]);
        }
    }
#ifdef DEBUG_NORM
    c[MPV_256_56]=1;
    c[MNV_256_56]=0;
#endif

}

/* Set c=a*b */
/* SU= 72 */
void BIG_256_56_mul(DBIG_256_56 c,BIG_256_56 a,BIG_256_56 b)
{
    int i;
#ifdef dchunk
    dchunk t,co;
    dchunk s;
    dchunk d[NLEN_256_56];
    int k;
#endif

#ifdef DEBUG_NORM
    if ((a[MPV_256_56]!=1 && a[MPV_256_56]!=0) || a[MNV_256_56]!=0) printf("First input to mul not normed\n");
    if ((b[MPV_256_56]!=1 && b[MPV_256_56]!=0) || b[MNV_256_56]!=0) printf("Second input to mul not normed\n");
#endif

    /* Faster to Combafy it.. Let the compiler unroll the loops! */

#ifdef COMBA

    /* faster psuedo-Karatsuba method */
#ifdef UNWOUND

    /* Insert output of faster.c here */

#else
    for (i=0; i<NLEN_256_56; i++)
        d[i]=(dchunk)a[i]*b[i];

    s=d[0];
    t=s;
    c[0]=(chunk)t&BMASK_256_56;
    co=t>>BASEBITS_256_56;

    for (k=1; k<NLEN_256_56; k++)
    {
        s+=d[k];
        t=co+s;
        for (i=k; i>=1+k/2; i--) t+=(dchunk)(a[i]-a[k-i])*(b[k-i]-b[i]);
        c[k]=(chunk)t&BMASK_256_56;
        co=t>>BASEBITS_256_56;
    }
    for (k=NLEN_256_56; k<2*NLEN_256_56-1; k++)
    {
        s-=d[k-NLEN_256_56];
        t=co+s;
        for (i=NLEN_256_56-1; i>=1+k/2; i--) t+=(dchunk)(a[i]-a[k-i])*(b[k-i]-b[i]);
        c[k]=(chunk)t&BMASK_256_56;
        co=t>>BASEBITS_256_56;
    }
    c[2*NLEN_256_56-1]=(chunk)co;

#endif

#else
    int j;
    chunk carry;
    BIG_256_56_dzero(c);
    for (i=0; i<NLEN_256_56; i++)
    {
        carry=0;
        for (j=0; j<NLEN_256_56; j++)
            carry=muladd_256_56(a[i],b[j],carry,&c[i+j]);

        c[NLEN_256_56+i]=carry;
    }

#endif

#ifdef DEBUG_NORM
    c[DMPV_256_56]=1;
    c[DMNV_256_56]=0;
#endif
}

/* Set c=a*a */
/* SU= 80 */
void BIG_256_56_sqr(DBIG_256_56 c,BIG_256_56 a)
{
    int i,j;
#ifdef dchunk
    dchunk t,co;
#endif

#ifdef DEBUG_NORM
    if ((a[MPV_256_56]!=1 && a[MPV_256_56]!=0) || a[MNV_256_56]!=0) printf("Input to sqr not normed\n");
#endif
    /* Note 2*a[i] in loop below and extra addition */

#ifdef COMBA

#ifdef UNWOUND

    /* Insert output of faster.c here */

#else


    t=(dchunk)a[0]*a[0];
    c[0]=(chunk)t&BMASK_256_56;
    co=t>>BASEBITS_256_56;

    for (j=1; j<NLEN_256_56-1; )
    {
        t=(dchunk)a[j]*a[0];
        for (i=1; i<(j+1)/2; i++)
        {
            t+=(dchunk)a[j-i]*a[i];
        }
        t+=t;
        t+=co;
        c[j]=(chunk)t&BMASK_256_56;
        co=t>>BASEBITS_256_56;
        j++;
        t=(dchunk)a[j]*a[0];
        for (i=1; i<(j+1)/2; i++)
        {
            t+=(dchunk)a[j-i]*a[i];
        }
        t+=t;
        t+=co;
        t+=(dchunk)a[j/2]*a[j/2];
        c[j]=(chunk)t&BMASK_256_56;
        co=t>>BASEBITS_256_56;
        j++;
    }

    for (j=NLEN_256_56-1+NLEN_256_56%2; j<DNLEN_256_56-3; )
    {
        t=(dchunk)a[NLEN_256_56-1]*a[j-NLEN_256_56+1];
        for (i=j-NLEN_256_56+2; i<(j+1)/2; i++)
        {
            t+=(dchunk)a[j-i]*a[i];
        }
        t+=t;
        t+=co;
        c[j]=(chunk)t&BMASK_256_56;
        co=t>>BASEBITS_256_56;
        j++;
        t=(dchunk)a[NLEN_256_56-1]*a[j-NLEN_256_56+1];
        for (i=j-NLEN_256_56+2; i<(j+1)/2; i++)
        {
            t+=(dchunk)a[j-i]*a[i];
        }
        t+=t;
        t+=co;
        t+=(dchunk)a[j/2]*a[j/2];
        c[j]=(chunk)t&BMASK_256_56;
        co=t>>BASEBITS_256_56;
        j++;
    }

    t=(dchunk)a[NLEN_256_56-2]*a[NLEN_256_56-1];
    t+=t;
    t+=co;
    c[DNLEN_256_56-3]=(chunk)t&BMASK_256_56;
    co=t>>BASEBITS_256_56;

    t=(dchunk)a[NLEN_256_56-1]*a[NLEN_256_56-1]+co;
    c[DNLEN_256_56-2]=(chunk)t&BMASK_256_56;
    co=t>>BASEBITS_256_56;
    c[DNLEN_256_56-1]=(chunk)co;


#endif

#else
    chunk carry;
    BIG_256_56_dzero(c);
    for (i=0; i<NLEN_256_56; i++)
    {
        carry=0;
        for (j=i+1; j<NLEN_256_56; j++)
            carry=muladd_256_56(a[i],a[j],carry,&c[i+j]);
        c[NLEN_256_56+i]=carry;
    }

    for (i=0; i<DNLEN_256_56; i++) c[i]*=2;

    for (i=0; i<NLEN_256_56; i++)
        c[2*i+1]+=muladd_256_56(a[i],a[i],0,&c[2*i]);

    BIG_256_56_dnorm(c);
#endif


#ifdef DEBUG_NORM
    c[DMPV_256_56]=1;
    c[DMNV_256_56]=0;
#endif

}

/* Montgomery reduction */
void BIG_256_56_monty(BIG_256_56 a,BIG_256_56 md,chunk MC,DBIG_256_56 d)
{
    int i,k;

#ifdef dchunk
    dchunk t,c,s;
    dchunk dd[NLEN_256_56];
    chunk v[NLEN_256_56];
#endif

#ifdef COMBA

#ifdef UNWOUND

    /* Insert output of faster.c here */

#else

    t=d[0];
    v[0]=((chunk)t*MC)&BMASK_256_56;
    t+=(dchunk)v[0]*md[0];
    c=(t>>BASEBITS_256_56)+d[1];
    s=0;

    for (k=1; k<NLEN_256_56; k++)
    {
        t=c+s+(dchunk)v[0]*md[k];
        for (i=k-1; i>k/2; i--) t+=(dchunk)(v[k-i]-v[i])*(md[i]-md[k-i]);
        v[k]=((chunk)t*MC)&BMASK_256_56;
        t+=(dchunk)v[k]*md[0];
        c=(t>>BASEBITS_256_56)+d[k+1];
        dd[k]=(dchunk)v[k]*md[k];
        s+=dd[k];
    }
    for (k=NLEN_256_56; k<2*NLEN_256_56-1; k++)
    {
        t=c+s;
        for (i=NLEN_256_56-1; i>=1+k/2; i--) t+=(dchunk)(v[k-i]-v[i])*(md[i]-md[k-i]);
        a[k-NLEN_256_56]=(chunk)t&BMASK_256_56;
        c=(t>>BASEBITS_256_56)+d[k+1];
        s-=dd[k-NLEN_256_56+1];
    }
    a[NLEN_256_56-1]=(chunk)c&BMASK_256_56;

#endif

#ifdef DEBUG_NORM
    a[MPV_256_56]=1;
    a[MNV_256_56]=0;
#endif

#else
    int j;
    chunk m,carry;
    for (i=0; i<NLEN_256_56; i++)
    {
        if (MC==-1) m=(-d[i])&BMASK_256_56;
        else
        {
            if (MC==1) m=d[i];
            else m=(MC*d[i])&BMASK_256_56;
        }
        carry=0;
        for (j=0; j<NLEN_256_56; j++)
            carry=muladd_256_56(m,md[j],carry,&d[i+j]);
        d[NLEN_256_56+i]+=carry;
    }
    BIG_256_56_sducopy(a,d);
    BIG_256_56_norm(a);

#endif
}

/* General shift left of a by n bits */
/* a MUST be normalised */
/* SU= 32 */
void BIG_256_56_shl(BIG_256_56 a,int k)
{
    int i;
    int n=k%BASEBITS_256_56;
    int m=k/BASEBITS_256_56;

    a[NLEN_256_56-1]=((a[NLEN_256_56-1-m]<<n));
    if (NLEN_256_56>=m+2) a[NLEN_256_56-1]|=(a[NLEN_256_56-m-2]>>(BASEBITS_256_56-n));

    for (i=NLEN_256_56-2; i>m; i--)
        a[i]=((a[i-m]<<n)&BMASK_256_56)|(a[i-m-1]>>(BASEBITS_256_56-n));
    a[m]=(a[0]<<n)&BMASK_256_56;
    for (i=0; i<m; i++) a[i]=0;

}

/* Fast shift left of a by n bits, where n less than a word, Return excess (but store it as well) */
/* a MUST be normalised */
/* SU= 16 */
int BIG_256_56_fshl(BIG_256_56 a,int n)
{
    int i;

    a[NLEN_256_56-1]=((a[NLEN_256_56-1]<<n))|(a[NLEN_256_56-2]>>(BASEBITS_256_56-n)); /* top word not masked */
    for (i=NLEN_256_56-2; i>0; i--)
        a[i]=((a[i]<<n)&BMASK_256_56)|(a[i-1]>>(BASEBITS_256_56-n));
    a[0]=(a[0]<<n)&BMASK_256_56;

    return (int)(a[NLEN_256_56-1]>>((8*MODBYTES_256_56)%BASEBITS_256_56)); /* return excess - only used in ff.c */
}

/* double length left shift of a by k bits - k can be > BASEBITS , a MUST be normalised */
/* SU= 32 */
void BIG_256_56_dshl(DBIG_256_56 a,int k)
{
    int i;
    int n=k%BASEBITS_256_56;
    int m=k/BASEBITS_256_56;

    a[DNLEN_256_56-1]=((a[DNLEN_256_56-1-m]<<n))|(a[DNLEN_256_56-m-2]>>(BASEBITS_256_56-n));

    for (i=DNLEN_256_56-2; i>m; i--)
        a[i]=((a[i-m]<<n)&BMASK_256_56)|(a[i-m-1]>>(BASEBITS_256_56-n));
    a[m]=(a[0]<<n)&BMASK_256_56;
    for (i=0; i<m; i++) a[i]=0;

}

/* General shift rightof a by k bits */
/* a MUST be normalised */
/* SU= 32 */
void BIG_256_56_shr(BIG_256_56 a,int k)
{
    int i;
    int n=k%BASEBITS_256_56;
    int m=k/BASEBITS_256_56;
    for (i=0; i<NLEN_256_56-m-1; i++)
        a[i]=(a[m+i]>>n)|((a[m+i+1]<<(BASEBITS_256_56-n))&BMASK_256_56);
    if (NLEN_256_56>m)  a[NLEN_256_56-m-1]=a[NLEN_256_56-1]>>n;
    for (i=NLEN_256_56-m; i<NLEN_256_56; i++) a[i]=0;

}

/* Faster shift right of a by k bits. Return shifted out part */
/* a MUST be normalised */
/* SU= 16 */
int BIG_256_56_fshr(BIG_256_56 a,int k)
{
    int i;
    chunk r=a[0]&(((chunk)1<<k)-1); /* shifted out part */
    for (i=0; i<NLEN_256_56-1; i++)
        a[i]=(a[i]>>k)|((a[i+1]<<(BASEBITS_256_56-k))&BMASK_256_56);
    a[NLEN_256_56-1]=a[NLEN_256_56-1]>>k;
    return (int)r;
}

/* double length right shift of a by k bits - can be > BASEBITS */
/* SU= 32 */
void BIG_256_56_dshr(DBIG_256_56 a,int k)
{
    int i;
    int n=k%BASEBITS_256_56;
    int m=k/BASEBITS_256_56;
    for (i=0; i<DNLEN_256_56-m-1; i++)
        a[i]=(a[m+i]>>n)|((a[m+i+1]<<(BASEBITS_256_56-n))&BMASK_256_56);
    a[DNLEN_256_56-m-1]=a[DNLEN_256_56-1]>>n;
    for (i=DNLEN_256_56-m; i<DNLEN_256_56; i++ ) a[i]=0;
}

/* Split DBIG d into two BIGs t|b. Split happens at n bits, where n falls into NLEN word */
/* d MUST be normalised */
/* SU= 24 */
chunk BIG_256_56_split(BIG_256_56 t,BIG_256_56 b,DBIG_256_56 d,int n)
{
    int i;
    chunk nw,carry=0;
    int m=n%BASEBITS_256_56;
//	BIG_dnorm(d);

    if (m==0)
    {
        for (i=0; i<NLEN_256_56; i++) b[i]=d[i];
        if (t!=b)
        {
            for (i=NLEN_256_56; i<2*NLEN_256_56; i++) t[i-NLEN_256_56]=d[i];
            carry=t[NLEN_256_56-1]>>BASEBITS_256_56;
            t[NLEN_256_56-1]=t[NLEN_256_56-1]&BMASK_256_56; /* top word normalized */
        }
        return carry;
    }

    for (i=0; i<NLEN_256_56-1; i++) b[i]=d[i];

    b[NLEN_256_56-1]=d[NLEN_256_56-1]&(((chunk)1<<m)-1);

    if (t!=b)
    {
        carry=(d[DNLEN_256_56-1]<<(BASEBITS_256_56-m));
        for (i=DNLEN_256_56-2; i>=NLEN_256_56-1; i--)
        {
            nw=(d[i]>>m)|carry;
            carry=(d[i]<<(BASEBITS_256_56-m))&BMASK_256_56;
            t[i-NLEN_256_56+1]=nw;
        }
    }
#ifdef DEBUG_NORM
    t[MPV_256_56]=1;
    t[MNV_256_56]=0;
    b[MPV_256_56]=1;
    b[MNV_256_56]=0;
#endif
    return carry;
}

/* you gotta keep the sign of carry! Look - no branching! */
/* Note that sign bit is needed to disambiguate between +ve and -ve values */
/* normalise BIG - force all digits < 2^BASEBITS */
chunk BIG_256_56_norm(BIG_256_56 a)
{
    int i;
    chunk d,carry=0;
    for (i=0; i<NLEN_256_56-1; i++)
    {
        d=a[i]+carry;
        a[i]=d&BMASK_256_56;
        carry=d>>BASEBITS_256_56;
    }
    a[NLEN_256_56-1]=(a[NLEN_256_56-1]+carry);

#ifdef DEBUG_NORM
    a[MPV_256_56]=1;
    a[MNV_256_56]=0;
#endif
    return (a[NLEN_256_56-1]>>((8*MODBYTES_256_56)%BASEBITS_256_56));  /* only used in ff.c */
}

void BIG_256_56_dnorm(DBIG_256_56 a)
{
    int i;
    chunk d,carry=0;
    for (i=0; i<DNLEN_256_56-1; i++)
    {
        d=a[i]+carry;
        a[i]=d&BMASK_256_56;
        carry=d>>BASEBITS_256_56;
    }
    a[DNLEN_256_56-1]=(a[DNLEN_256_56-1]+carry);
#ifdef DEBUG_NORM
    a[DMPV_256_56]=1;
    a[DMNV_256_56]=0;
#endif
}

/* Compare a and b. Return 1 for a>b, -1 for a<b, 0 for a==b */
/* a and b MUST be normalised before call */
int BIG_256_56_comp(BIG_256_56 a,BIG_256_56 b)
{
    int i;
    for (i=NLEN_256_56-1; i>=0; i--)
    {
        if (a[i]==b[i]) continue;
        if (a[i]>b[i]) return 1;
        else  return -1;
    }
    return 0;
}

int BIG_256_56_dcomp(DBIG_256_56 a,DBIG_256_56 b)
{
    int i;
    for (i=DNLEN_256_56-1; i>=0; i--)
    {
        if (a[i]==b[i]) continue;
        if (a[i]>b[i]) return 1;
        else  return -1;
    }
    return 0;
}

/* return number of bits in a */
/* SU= 8 */
int BIG_256_56_nbits(BIG_256_56 a)
{
    int bts,k=NLEN_256_56-1;
    chunk c;
    BIG_256_56_norm(a);
    while (k>=0 && a[k]==0) k--;
    if (k<0) return 0;
    bts=BASEBITS_256_56*k;
    c=a[k];
    while (c!=0)
    {
        c/=2;
        bts++;
    }
    return bts;
}

/* SU= 8, Calculate number of bits in a DBIG - output normalised */
int BIG_256_56_dnbits(DBIG_256_56 a)
{
    int bts,k=DNLEN_256_56-1;
    chunk c;
    BIG_256_56_dnorm(a);
    while (k>=0 && a[k]==0) k--;
    if (k<0) return 0;
    bts=BASEBITS_256_56*k;
    c=a[k];
    while (c!=0)
    {
        c/=2;
        bts++;
    }
    return bts;
}


/* Set b=b mod c */
/* SU= 16 */
void BIG_256_56_mod(BIG_256_56 b,BIG_256_56 c)
{
    int k=0;
    BIG_256_56 r; /**/

    BIG_256_56_norm(b);
    if (BIG_256_56_comp(b,c)<0)
        return;
    do
    {
        BIG_256_56_fshl(c,1);
        k++;
    }
    while (BIG_256_56_comp(b,c)>=0);

    while (k>0)
    {
        BIG_256_56_fshr(c,1);

// constant time...
        BIG_256_56_sub(r,b,c);
        BIG_256_56_norm(r);
        BIG_256_56_cmove(b,r,1-((r[NLEN_256_56-1]>>(CHUNK-1))&1));
        k--;
    }
}

/* Set a=b mod c, b is destroyed. Slow but rarely used. */
/* SU= 96 */
void BIG_256_56_dmod(BIG_256_56 a,DBIG_256_56 b,BIG_256_56 c)
{
    int k=0;
    DBIG_256_56 m,r;
    BIG_256_56_dnorm(b);
    BIG_256_56_dscopy(m,c);

    if (BIG_256_56_dcomp(b,m)<0)
    {
        BIG_256_56_sdcopy(a,b);
        return;
    }

    do
    {
        BIG_256_56_dshl(m,1);
        k++;
    }
    while (BIG_256_56_dcomp(b,m)>=0);

    while (k>0)
    {
        BIG_256_56_dshr(m,1);
// constant time...
        BIG_256_56_dsub(r,b,m);
        BIG_256_56_dnorm(r);
        BIG_256_56_dcmove(b,r,1-((r[DNLEN_256_56-1]>>(CHUNK-1))&1));

        k--;
    }
    BIG_256_56_sdcopy(a,b);
}

/* Set a=b/c,  b is destroyed. Slow but rarely used. */
/* SU= 136 */

void BIG_256_56_ddiv(BIG_256_56 a,DBIG_256_56 b,BIG_256_56 c)
{
    int d,k=0;
    DBIG_256_56 m,dr;
    BIG_256_56 e,r;
    BIG_256_56_dnorm(b);
    BIG_256_56_dscopy(m,c);

    BIG_256_56_zero(a);
    BIG_256_56_zero(e);
    BIG_256_56_inc(e,1);

    while (BIG_256_56_dcomp(b,m)>=0)
    {
        BIG_256_56_fshl(e,1);
        BIG_256_56_dshl(m,1);
        k++;
    }

    while (k>0)
    {
        BIG_256_56_dshr(m,1);
        BIG_256_56_fshr(e,1);

        BIG_256_56_dsub(dr,b,m);
        BIG_256_56_dnorm(dr);
        d=1-((dr[DNLEN_256_56-1]>>(CHUNK-1))&1);
        BIG_256_56_dcmove(b,dr,d);

        BIG_256_56_add(r,a,e);
        BIG_256_56_norm(r);
        BIG_256_56_cmove(a,r,d);

        k--;
    }
}

/* SU= 136 */

void BIG_256_56_sdiv(BIG_256_56 a,BIG_256_56 c)
{
    int d,k=0;
    BIG_256_56 m,e,b,r;
    BIG_256_56_norm(a);
    BIG_256_56_copy(b,a);
    BIG_256_56_copy(m,c);

    BIG_256_56_zero(a);
    BIG_256_56_zero(e);
    BIG_256_56_inc(e,1);

    while (BIG_256_56_comp(b,m)>=0)
    {
        BIG_256_56_fshl(e,1);
        BIG_256_56_fshl(m,1);
        k++;
    }

    while (k>0)
    {
        BIG_256_56_fshr(m,1);
        BIG_256_56_fshr(e,1);

        BIG_256_56_sub(r,b,m);
        BIG_256_56_norm(r);
        d=1-((r[NLEN_256_56-1]>>(CHUNK-1))&1);
        BIG_256_56_cmove(b,r,d);

        BIG_256_56_add(r,a,e);
        BIG_256_56_norm(r);
        BIG_256_56_cmove(a,r,d);
        k--;
    }
}

/* return LSB of a */
int BIG_256_56_parity(BIG_256_56 a)
{
    return a[0]%2;
}

/* return n-th bit of a */
/* SU= 16 */
int BIG_256_56_bit(BIG_256_56 a,int n)
{
    if (a[n/BASEBITS_256_56]&((chunk)1<<(n%BASEBITS_256_56))) return 1;
    else return 0;
}

/* return NAF value as +/- 1, 3 or 5. x and x3 should be normed.
nbs is number of bits processed, and nzs is number of trailing 0s detected */
/* SU= 32 */
/*
int BIG_nafbits(BIG x,BIG x3,int i,int *nbs,int *nzs)
{
	int j,r,nb;

	nb=BIG_bit(x3,i)-BIG_bit(x,i);
	*nbs=1;
	*nzs=0;
	if (nb==0) return 0;
	if (i==0) return nb;

    if (nb>0) r=1;
    else      r=(-1);

    for (j=i-1;j>0;j--)
    {
        (*nbs)++;
        r*=2;
        nb=BIG_bit(x3,j)-BIG_bit(x,j);
        if (nb>0) r+=1;
        if (nb<0) r-=1;
        if (abs(r)>5) break;
    }

	if (r%2!=0 && j!=0)
    { // backtrack
        if (nb>0) r=(r-1)/2;
        if (nb<0) r=(r+1)/2;
        (*nbs)--;
    }

    while (r%2==0)
    { // remove trailing zeros
        r/=2;
        (*nzs)++;
        (*nbs)--;
    }
    return r;
}
*/

/* return last n bits of a, where n is small < BASEBITS */
/* SU= 16 */
int BIG_256_56_lastbits(BIG_256_56 a,int n)
{
    int msk=(1<<n)-1;
    BIG_256_56_norm(a);
    return ((int)a[0])&msk;
}

/* get 8*MODBYTES size random number */
void BIG_256_56_random(BIG_256_56 m,csprng *rng)
{
    int i,b,j=0,r=0;
    int len=8*MODBYTES_256_56;

    BIG_256_56_zero(m);
    /* generate random BIG */
    for (i=0; i<len; i++)
    {
        if (j==0) r=RAND_byte(rng);
        else r>>=1;
        b=r&1;
        BIG_256_56_shl(m,1);
        m[0]+=b;
        j++;
        j&=7;
    }

#ifdef DEBUG_NORM
    m[MPV_256_56]=1;
    m[MNV_256_56]=0;
#endif
}

/* get random BIG from rng, modulo q. Done one bit at a time, so its portable */

void BIG_256_56_randomnum(BIG_256_56 m,BIG_256_56 q,csprng *rng)
{
    int i,b,j=0,r=0;
    DBIG_256_56 d;
    BIG_256_56_dzero(d);
    /* generate random DBIG */
    for (i=0; i<2*BIG_256_56_nbits(q); i++)
    {
        if (j==0) r=RAND_byte(rng);
        else r>>=1;
        b=r&1;
        BIG_256_56_dshl(d,1);
        d[0]+=b;
        j++;
        j&=7;
    }
    /* reduce modulo a BIG. Removes bias */
    BIG_256_56_dmod(m,d,q);
#ifdef DEBUG_NORM
    m[MPV_256_56]=1;
    m[MNV_256_56]=0;
#endif
}

/* Set r=a*b mod m */
/* SU= 96 */
void BIG_256_56_modmul(BIG_256_56 r,BIG_256_56 a,BIG_256_56 b,BIG_256_56 m)
{
    DBIG_256_56 d;
    BIG_256_56_mod(a,m);
    BIG_256_56_mod(b,m);

    BIG_256_56_mul(d,a,b);
    BIG_256_56_dmod(r,d,m);
}

/* Set a=a*a mod m */
/* SU= 88 */
void BIG_256_56_modsqr(BIG_256_56 r,BIG_256_56 a,BIG_256_56 m)
{
    DBIG_256_56 d;
    BIG_256_56_mod(a,m);
    BIG_256_56_sqr(d,a);
    BIG_256_56_dmod(r,d,m);
}

/* Set r=-a mod m */
/* SU= 16 */
void BIG_256_56_modneg(BIG_256_56 r,BIG_256_56 a,BIG_256_56 m)
{
    BIG_256_56_mod(a,m);
    BIG_256_56_sub(r,m,a);
    BIG_256_56_mod(r,m);
}

/* Set a=a/b mod m */
/* SU= 136 */
void BIG_256_56_moddiv(BIG_256_56 r,BIG_256_56 a,BIG_256_56 b,BIG_256_56 m)
{
    DBIG_256_56 d;
    BIG_256_56 z;
    BIG_256_56_mod(a,m);
    BIG_256_56_invmodp(z,b,m);

    BIG_256_56_mul(d,a,z);
    BIG_256_56_dmod(r,d,m);
}

/* Get jacobi Symbol (a/p). Returns 0, 1 or -1 */
/* SU= 216 */
int BIG_256_56_jacobi(BIG_256_56 a,BIG_256_56 p)
{
    int n8,k,m=0;
    BIG_256_56 t,x,n,zilch,one;
    BIG_256_56_one(one);
    BIG_256_56_zero(zilch);
    if (BIG_256_56_parity(p)==0 || BIG_256_56_comp(a,zilch)==0 || BIG_256_56_comp(p,one)<=0) return 0;
    BIG_256_56_norm(a);
    BIG_256_56_copy(x,a);
    BIG_256_56_copy(n,p);
    BIG_256_56_mod(x,p);

    while (BIG_256_56_comp(n,one)>0)
    {
        if (BIG_256_56_comp(x,zilch)==0) return 0;
        n8=BIG_256_56_lastbits(n,3);
        k=0;
        while (BIG_256_56_parity(x)==0)
        {
            k++;
            BIG_256_56_shr(x,1);
        }
        if (k%2==1) m+=(n8*n8-1)/8;
        m+=(n8-1)*(BIG_256_56_lastbits(x,2)-1)/4;
        BIG_256_56_copy(t,n);

        BIG_256_56_mod(t,x);
        BIG_256_56_copy(n,x);
        BIG_256_56_copy(x,t);
        m%=2;

    }
    if (m==0) return 1;
    else return -1;
}

/* Set r=1/a mod p. Binary method */
/* SU= 240 */
void BIG_256_56_invmodp(BIG_256_56 r,BIG_256_56 a,BIG_256_56 p)
{
    BIG_256_56 u,v,x1,x2,t,one;
    BIG_256_56_mod(a,p);
    BIG_256_56_copy(u,a);
    BIG_256_56_copy(v,p);
    BIG_256_56_one(one);
    BIG_256_56_copy(x1,one);
    BIG_256_56_zero(x2);

    while (BIG_256_56_comp(u,one)!=0 && BIG_256_56_comp(v,one)!=0)
    {
        while (BIG_256_56_parity(u)==0)
        {
            BIG_256_56_shr(u,1);
            if (BIG_256_56_parity(x1)!=0)
            {
                BIG_256_56_add(x1,p,x1);
                BIG_256_56_norm(x1);
            }
            BIG_256_56_shr(x1,1);
        }
        while (BIG_256_56_parity(v)==0)
        {
            BIG_256_56_shr(v,1);
            if (BIG_256_56_parity(x2)!=0)
            {
                BIG_256_56_add(x2,p,x2);
                BIG_256_56_norm(x2);
            }
            BIG_256_56_shr(x2,1);
        }
        if (BIG_256_56_comp(u,v)>=0)
        {
            BIG_256_56_sub(u,u,v);
            BIG_256_56_norm(u);
            if (BIG_256_56_comp(x1,x2)>=0) BIG_256_56_sub(x1,x1,x2);
            else
            {
                BIG_256_56_sub(t,p,x2);
                BIG_256_56_add(x1,x1,t);
            }
            BIG_256_56_norm(x1);
        }
        else
        {
            BIG_256_56_sub(v,v,u);
            BIG_256_56_norm(v);
            if (BIG_256_56_comp(x2,x1)>=0) BIG_256_56_sub(x2,x2,x1);
            else
            {
                BIG_256_56_sub(t,p,x1);
                BIG_256_56_add(x2,x2,t);
            }
            BIG_256_56_norm(x2);
        }
    }
    if (BIG_256_56_comp(u,one)==0)
        BIG_256_56_copy(r,x1);
    else
        BIG_256_56_copy(r,x2);
}

/* set x = x mod 2^m */
void BIG_256_56_mod2m(BIG_256_56 x,int m)
{
    int i,wd,bt;
    chunk msk;
    BIG_256_56_norm(x);
//	if (m>=MODBITS) return;
    wd=m/BASEBITS_256_56;
    bt=m%BASEBITS_256_56;
    msk=((chunk)1<<bt)-1;
    x[wd]&=msk;
    for (i=wd+1; i<NLEN_256_56; i++) x[i]=0;
}

// new
/* Convert to DBIG number from byte array of given length */
void BIG_256_56_dfromBytesLen(DBIG_256_56 a,char *b,int s)
{
    int i,len=s;
    BIG_256_56_dzero(a);

    for (i=0; i<len; i++)
    {
        BIG_256_56_dshl(a,8);
        a[0]+=(int)(unsigned char)b[i];
    }
#ifdef DEBUG_NORM
    a[DMPV_256_56]=1;
    a[DMNV_256_56]=0;
#endif
}