/***********************************************************************************
* FourQlib: a high-performance crypto library based on the elliptic curve FourQ
*
*    Copyright (c) Microsoft Corporation. All rights reserved.
*
* Abstract: table lookup functions
************************************************************************************/

#ifndef __TABLE_LOOKUP_H__
#define __TABLE_LOOKUP_H__


// For C++
#ifdef __cplusplus
extern "C" {
#endif


#include "FourQ_internal.h"


void table_lookup_1x8(point_extproj_precomp_t* table, point_extproj_precomp_t P, unsigned int digit, unsigned int sign_mask)
{ // Constant-time table lookup to extract a point represented as (X+Y,Y-X,2Z,2dT) corresponding to extended twisted Edwards coordinates (X:Y:Z:T)
  // Inputs: sign_mask, digit, table containing 8 points
  // Output: P = sign*table[digit], where sign=1 if sign_mask=0xFF...FF and sign=-1 if sign_mask=0

#if defined(NO_CACHE_MEM)
    point_extproj_precomp_t temp_point[2];

    ecccopy_precomp(table[digit], temp_point[1]);                            // temp_point[1] = table[digit]
    fp2copy1271(temp_point[1]->xy, temp_point[0]->yx);                       // temp_point[0] = -table[digit], i.e., coordinates (y-x,x+y,2*z,-2dt)
    fp2copy1271(temp_point[1]->yx, temp_point[0]->xy);     
    fp2copy1271(temp_point[1]->t2, temp_point[0]->t2);                                   
    fp2copy1271(temp_point[1]->z2, temp_point[0]->z2);                                                                 
    fpneg1271(temp_point[0]->t2[0]);                                          
    fpneg1271(temp_point[0]->t2[1]);   
    ecccopy_precomp(temp_point[sign_mask & 1], P);           

#else
    point_extproj_precomp_t point, temp_point;
    unsigned int i, j;
    digit_t mask;
                                  
    ecccopy_precomp(table[0], point);                                        // point = table[0]

    for (i = 1; i < 8; i++)
    {
        digit--;
        // While digit>=0 mask = 0xFF...F else sign = 0x00...0
        mask = ((digit_t)digit >> (RADIX-1)) - 1;
        ecccopy_precomp(table[i], temp_point);                               // temp_point = table[i] 
        // If mask = 0x00...0 then point = point, else if mask = 0xFF...F then point = temp_point            
        point->xy[0][0] = (mask & (point->xy[0][0] ^ temp_point->xy[0][0])) ^ point->xy[0][0];
        point->xy[0][1] = (mask & (point->xy[0][1] ^ temp_point->xy[0][1])) ^ point->xy[0][1];
        point->xy[0][2] = (mask & (point->xy[0][2] ^ temp_point->xy[0][2])) ^ point->xy[0][2];
        point->xy[0][3] = (mask & (point->xy[0][3] ^ temp_point->xy[0][3])) ^ point->xy[0][3];
        point->xy[1][0] = (mask & (point->xy[1][0] ^ temp_point->xy[1][0])) ^ point->xy[1][0];
        point->xy[1][1] = (mask & (point->xy[1][1] ^ temp_point->xy[1][1])) ^ point->xy[1][1];
        point->xy[1][2] = (mask & (point->xy[1][2] ^ temp_point->xy[1][2])) ^ point->xy[1][2];
        point->xy[1][3] = (mask & (point->xy[1][3] ^ temp_point->xy[1][3])) ^ point->xy[1][3];
        point->yx[0][0] = (mask & (point->yx[0][0] ^ temp_point->yx[0][0])) ^ point->yx[0][0];
        point->yx[0][1] = (mask & (point->yx[0][1] ^ temp_point->yx[0][1])) ^ point->yx[0][1];
        point->yx[0][2] = (mask & (point->yx[0][2] ^ temp_point->yx[0][2])) ^ point->yx[0][2];
        point->yx[0][3] = (mask & (point->yx[0][3] ^ temp_point->yx[0][3])) ^ point->yx[0][3];
        point->yx[1][0] = (mask & (point->yx[1][0] ^ temp_point->yx[1][0])) ^ point->yx[1][0];
        point->yx[1][1] = (mask & (point->yx[1][1] ^ temp_point->yx[1][1])) ^ point->yx[1][1];
        point->yx[1][2] = (mask & (point->yx[1][2] ^ temp_point->yx[1][2])) ^ point->yx[1][2];
        point->yx[1][3] = (mask & (point->yx[1][3] ^ temp_point->yx[1][3])) ^ point->yx[1][3];
        point->z2[0][0] = (mask & (point->z2[0][0] ^ temp_point->z2[0][0])) ^ point->z2[0][0];
        point->z2[0][1] = (mask & (point->z2[0][1] ^ temp_point->z2[0][1])) ^ point->z2[0][1];
        point->z2[0][2] = (mask & (point->z2[0][2] ^ temp_point->z2[0][2])) ^ point->z2[0][2];
        point->z2[0][3] = (mask & (point->z2[0][3] ^ temp_point->z2[0][3])) ^ point->z2[0][3];
        point->z2[1][0] = (mask & (point->z2[1][0] ^ temp_point->z2[1][0])) ^ point->z2[1][0];
        point->z2[1][1] = (mask & (point->z2[1][1] ^ temp_point->z2[1][1])) ^ point->z2[1][1];
        point->z2[1][2] = (mask & (point->z2[1][2] ^ temp_point->z2[1][2])) ^ point->z2[1][2];
        point->z2[1][3] = (mask & (point->z2[1][3] ^ temp_point->z2[1][3])) ^ point->z2[1][3];
        point->t2[0][0] = (mask & (point->t2[0][0] ^ temp_point->t2[0][0])) ^ point->t2[0][0];
        point->t2[0][1] = (mask & (point->t2[0][1] ^ temp_point->t2[0][1])) ^ point->t2[0][1];
        point->t2[0][2] = (mask & (point->t2[0][2] ^ temp_point->t2[0][2])) ^ point->t2[0][2];
        point->t2[0][3] = (mask & (point->t2[0][3] ^ temp_point->t2[0][3])) ^ point->t2[0][3];
        point->t2[1][0] = (mask & (point->t2[1][0] ^ temp_point->t2[1][0])) ^ point->t2[1][0];
        point->t2[1][1] = (mask & (point->t2[1][1] ^ temp_point->t2[1][1])) ^ point->t2[1][1];
        point->t2[1][2] = (mask & (point->t2[1][2] ^ temp_point->t2[1][2])) ^ point->t2[1][2];
        point->t2[1][3] = (mask & (point->t2[1][3] ^ temp_point->t2[1][3])) ^ point->t2[1][3];
    }
    
    fp2copy1271(point->t2, temp_point->t2);
    fp2copy1271(point->xy, temp_point->yx);                                  // point: x+y,y-x,2dt coordinate, temp_point: y-x,x+y,-2dt coordinate
    fp2copy1271(point->yx, temp_point->xy);                                   
    fpneg1271(temp_point->t2[0]);                                            // Negate 2dt coordinate
    fpneg1271(temp_point->t2[1]);             
    for (j = 0; j < NWORDS_FIELD; j++) {                                     // If sign_mask = 0 then choose negative of the point
        point->xy[0][j] = ((digit_t)((int)sign_mask) & (point->xy[0][j] ^ temp_point->xy[0][j])) ^ temp_point->xy[0][j];
        point->xy[1][j] = ((digit_t)((int)sign_mask) & (point->xy[1][j] ^ temp_point->xy[1][j])) ^ temp_point->xy[1][j];
        point->yx[0][j] = ((digit_t)((int)sign_mask) & (point->yx[0][j] ^ temp_point->yx[0][j])) ^ temp_point->yx[0][j];
        point->yx[1][j] = ((digit_t)((int)sign_mask) & (point->yx[1][j] ^ temp_point->yx[1][j])) ^ temp_point->yx[1][j];
        point->t2[0][j] = ((digit_t)((int)sign_mask) & (point->t2[0][j] ^ temp_point->t2[0][j])) ^ temp_point->t2[0][j];
        point->t2[1][j] = ((digit_t)((int)sign_mask) & (point->t2[1][j] ^ temp_point->t2[1][j])) ^ temp_point->t2[1][j];
    }                                
    ecccopy_precomp(point, P); 
#endif
}


void table_lookup_fixed_base(point_precomp_t* table, point_precomp_t P, unsigned int digit, unsigned int sign)
{ // Constant-time table lookup to extract a point represented as (x+y,y-x,2t) corresponding to extended twisted Edwards coordinates (X:Y:Z:T) with Z=1
  // Inputs: sign, digit, table containing VPOINTS_FIXEDBASE = 2^(W_FIXEDBASE-1) points
  // Output: if sign=0 then P = table[digit], else if (sign=-1) then P = -table[digit]

#if defined(NO_CACHE_MEM)
    point_precomp_t temp_point[2];

    ecccopy_precomp_fixed_base(table[digit], temp_point[0]);                 // temp_point[0] = table[digit]
    fp2copy1271(temp_point[0]->xy, temp_point[1]->yx);                       // temp_point[1] = -table[digit], i.e., coordinates (y-x,x+y,2*z,-2dt)
    fp2copy1271(temp_point[0]->yx, temp_point[1]->xy);     
    fp2copy1271(temp_point[0]->t2, temp_point[1]->t2);                                                                 
    fpneg1271(temp_point[1]->t2[0]);                                          
    fpneg1271(temp_point[1]->t2[1]);   
    ecccopy_precomp_fixed_base(temp_point[sign & 1], P);    

#else
    point_precomp_t point, temp_point;
    unsigned int i, j;
    digit_t mask;
                                   
    ecccopy_precomp_fixed_base(table[0], point);                             // point = table[0]

    for (i = 1; i < VPOINTS_FIXEDBASE; i++)
    {
        digit--;
        // While digit>=0 mask = 0xFF...F else sign = 0x00...0
        mask = ((digit_t)digit >> (RADIX-1)) - 1;
        ecccopy_precomp_fixed_base(table[i], temp_point);                    // temp_point = table[i] 
        // If mask = 0x00...0 then point = point, else if mask = 0xFF...F then point = temp_point
        for (j = 0; j < NWORDS_FIELD; j++) {
            point->xy[0][j] = (mask & (point->xy[0][j] ^ temp_point->xy[0][j])) ^ point->xy[0][j];
            point->xy[1][j] = (mask & (point->xy[1][j] ^ temp_point->xy[1][j])) ^ point->xy[1][j];
            point->yx[0][j] = (mask & (point->yx[0][j] ^ temp_point->yx[0][j])) ^ point->yx[0][j];
            point->yx[1][j] = (mask & (point->yx[1][j] ^ temp_point->yx[1][j])) ^ point->yx[1][j];
            point->t2[0][j] = (mask & (point->t2[0][j] ^ temp_point->t2[0][j])) ^ point->t2[0][j];
            point->t2[1][j] = (mask & (point->t2[1][j] ^ temp_point->t2[1][j])) ^ point->t2[1][j];
        }
    }
    
    fp2copy1271(point->t2, temp_point->t2);
    fp2copy1271(point->xy, temp_point->yx);                                  // point: x+y,y-x,2dt coordinate, temp_point: y-x,x+y,-2dt coordinate
    fp2copy1271(point->yx, temp_point->xy);                                   
    fpneg1271(temp_point->t2[0]);                                            // Negate 2dt coordinate
    fpneg1271(temp_point->t2[1]);             
    for (j = 0; j < NWORDS_FIELD; j++) {                                     // If sign = 0xFF...F then choose negative of the point
        point->xy[0][j] = ((digit_t)((int)sign) & (point->xy[0][j] ^ temp_point->xy[0][j])) ^ point->xy[0][j];
        point->xy[1][j] = ((digit_t)((int)sign) & (point->xy[1][j] ^ temp_point->xy[1][j])) ^ point->xy[1][j];
        point->yx[0][j] = ((digit_t)((int)sign) & (point->yx[0][j] ^ temp_point->yx[0][j])) ^ point->yx[0][j];
        point->yx[1][j] = ((digit_t)((int)sign) & (point->yx[1][j] ^ temp_point->yx[1][j])) ^ point->yx[1][j];
        point->t2[0][j] = ((digit_t)((int)sign) & (point->t2[0][j] ^ temp_point->t2[0][j])) ^ point->t2[0][j];
        point->t2[1][j] = ((digit_t)((int)sign) & (point->t2[1][j] ^ temp_point->t2[1][j])) ^ point->t2[1][j];
    }                                  
    ecccopy_precomp_fixed_base(point, P);
#endif
}


#ifdef __cplusplus
}
#endif


#endif