Merge other basic circuits here

circuits/binsum.circom

@@ -0,0 +1,93 @@
+/*
+    Copyright 2018 0KIMS association.
+
+    This file is part of circom (Zero Knowledge Circuit Compiler).
+
+    circom is a 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 3 of the License, or
+    (at your option) any later version.
+
+    circom 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 circom. If not, see <https://www.gnu.org/licenses/>.
+*/
+
+/*
+
+Binary Sum
+==========
+
+This component creates a binary sum componet of ops operands and n bits each operand.
+
+e is Number of carries: Depends on the number of operands in the input.
+
+Main Constraint:
+   in[0][0]     * 2^0  +  in[0][1]     * 2^1  + ..... + in[0][n-1]    * 2^(n-1)  +
+ + in[1][0]     * 2^0  +  in[1][1]     * 2^1  + ..... + in[1][n-1]    * 2^(n-1)  +
+ + ..
+ + in[ops-1][0] * 2^0  +  in[ops-1][1] * 2^1  + ..... + in[ops-1][n-1] * 2^(n-1)  +
+ ===
+   out[0] * 2^0  + out[1] * 2^1 +   + out[n+e-1] *2(n+e-1)
+
+To waranty binary outputs:
+
+    out[0]     * (out[0] - 1) === 0
+    out[1]     * (out[0] - 1) === 0
+    .
+    .
+    .
+    out[n+e-1] * (out[n+e-1] - 1) == 0
+
+ */
+
+
+/*
+    This function calculates the number of extra bits in the output to do the full sum.
+ */
+
+function nbits(a) {
+    var n = 1;
+    var r = 0;
+    while (n-1<a) {
+        r++;
+        n *= 2;
+    }
+    return r;
+}
+
+
+template BinSum(n, ops) {
+    var nout = nbits((2**n -1)*ops);
+    signal input in[ops][n];
+    signal output out[nout];
+
+    var lin = 0;
+    var lout = 0;
+
+    var k;
+    var j;
+
+    for (k=0; k<n; k++) {
+        for (j=0; j<ops; j++) {
+            lin += in[j][k] * 2**k;
+        }
+    }
+
+    for (k=0; k<nout; k++) {
+        out[k] <-- (lin >> k) & 1;
+
+        // Ensure out is binary
+        out[k] * (out[k] - 1) === 0;
+
+        lout += out[k] * 2**k;
+    }
+
+    // Ensure the sum;
+
+    lin === lout;
+}