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74 lines
1.4 KiB
74 lines
1.4 KiB
/*
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Binary Sum
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==========
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This component creates a binary sum componet of ops operands and n bits each operand.
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e is Number of carries: Depends on the number of operands in the input.
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Main Constrain:
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in[0][0] * 2^0 + in[0][1] * 2^1 + ..... + in[0][n-1] * 2^(n-1) +
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+ in[1][0] * 2^0 + in[1][1] * 2^1 + ..... + in[1][n-1] * 2^(n-1) +
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+ ..
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+ in[ops-1][0] * 2^0 + in[ops-1][1] * 2^1 + ..... + in[ops-1][n-1] * 2^(n-1) +
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===
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out[0] * 2^0 + out[1] * 2^1 + + out[n+e-1] *2(n+e-1)
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To waranty binary outputs:
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out[0] * (out[0] - 1) === 0
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out[1] * (out[0] - 1) === 0
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.
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.
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.
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out[n+e-1] * (out[n+e-1] - 1) == 0
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*/
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/*
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This function calculates the number of extra bits in the output to do the full sum.
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*/
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function nbits(a) {
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var n = 1;
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var r = 0;
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while (n-1<a) {
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r++;
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n *= 2;
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}
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return r;
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}
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template BinSum(n, ops) {
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var nout = nbits((2**n -1)*ops);
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signal input in[ops][n];
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signal output out[nout];
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var lin = 0;
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var lout = 0;
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var k;
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var j;
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for (k=0; k<n; k++) {
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for (j=0; j<ops; j++) {
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lin += in[j][k] * 2**k;
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}
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}
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for (k=0; k<nout; k++) {
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out[k] <-- (lin >> k) & 1;
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// Ensure out is binary
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out[k] * (out[k] - 1) === 0;
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lout += out[k] * 2**k;
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}
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// Ensure the sum;
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lin === lout;
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}
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