图像缩放float 乘法

在图像缩放处理步骤中，关于图片的缩放前后所选取的坐标精度计算。
verilog与c++计算存在的结果不一致情况，就debug完毕后的思路以c++形式写出

px为float乘
px_i为verilog思路

int main(){

    for (int i = 1; i <= 8192; ++i){
        for(int j = 1; j <= 8192; ++j){
            for(int k = 1; k <= j; ++k){
                //px
                float scale = i / (float) j;
                int i_tmp;
                memcpy(&i_tmp, &scale, 4);
                int i_tmp2 = i_tmp & 0xffffffff;
                memcpy(&scale, &i_tmp2, 4);
                int px   = (int) (scale *(float)k);
                if( (scale>128.0) || ( scale < ( 1.0/128 ) ) ){
                    continue;
                }

                //px_i
                int i_tmp_frac = i_tmp2 & 0x007fffff;
                long real_frac  = i_tmp_frac | 0x00800000;
                int i_tmp_exp  = (i_tmp2 & 0x7f800000) >> 23;
                int real_exp   = i_tmp_exp - 127;

                float k_f = (float) k;
                memcpy(&i_tmp, &k_f, 4);
                int i_tmp_frac_k = i_tmp & 0x007fffff;
                long real_frac_k = i_tmp_frac_k | 0x00800000;
                int i_tmp_exp_k  = (i_tmp & 0x7f800000) >> 23;
                int real_exp_k   = i_tmp_exp_k - 127;

                long long mut_sk = real_frac_k * real_frac;

                bool more2    = mut_sk & 0x0000800000000000;
                mut_sk = more2? mut_sk : (mut_sk << 1);
                bool mut_odd  = mut_sk & 0x0000000001000000;
                bool mut_half = mut_sk & 0x0000000000800000; 
                bool more_half= (mut_sk & 0x00000000007fffff);
                int add_pre = ( mut_half && (mut_odd || more_half) ) ?  1 : 0;
                long long mut_sk_r = (mut_sk & 0x0000ffffff000000) + (add_pre << 24);                

                int px_i ;
                int res_exp =  (46 - real_exp - real_exp_k) + (more2 ? 0 : 1);
                px_i = mut_sk_r >> res_exp;
                if(px_i != px){
                    cout << endl;
                    cout << dec << i <<" "<< j << " " << k << " " << scale << " " << px << " " << px_i << endl;
                    cout << hex <<  mut_sk << endl;
                    cout << hex <<  mut_sk_r << endl;
                    cout << dec <<  add_pre << endl;
                    return 0;
                }
            }            
        }
        cout << setiosflags(ios::fixed) <<setprecision(2) <<( i / 8192.0 * 100) << "%\r" << flush;
    }

}

本文地址：https://blog.csdn.net/qq_15421283/article/details/108852882