diff --git a/c/main.cpp b/c/main.cpp
index 1d9f700..26d3167 100644
--- a/c/main.cpp
+++ b/c/main.cpp
@@ -100,7 +100,14 @@ void loadJson(Circom_CalcWit *ctx, std::string filename) {
     for (json::iterator it = j.begin(); it != j.end(); ++it) {
 //      std::cout << it.key() << " => " << it.value() << '\n';
       u64 h = fnv1a(it.key());
-      int o = ctx->getSignalOffset(0, h);
+      int o;
+      try {
+        o = ctx->getSignalOffset(0, h);
+      } catch (std::runtime_error e) {
+        std::ostringstream errStrStream;
+        errStrStream << "Error loadin variable: " << it.key() << "\n" << e.what();
+        throw std::runtime_error(errStrStream.str() );
+      }
       Circom_Sizes sizes = ctx->getSignalSizes(0, h);
       iterateArr(ctx, o, sizes, it.value(), itFunc);
     }
diff --git a/src/c_gen.js b/src/c_gen.js
index 67a2755..bb845de 100644
--- a/src/c_gen.js
+++ b/src/c_gen.js
@@ -229,11 +229,11 @@ function gen(ctx, ast) {
     } else if (ast.type == "BLOCK") {
         return genBlock(ctx, ast);
     } else if (ast.type == "COMPUTE") {
-        return genCompute(ctx, ast);
+        return gen(ctx, ast.body);
     } else if (ast.type == "FOR") {
-        return genFor(ctx, ast);
+        return genLoop(ctx, ast);
     } else if (ast.type == "WHILE") {
-        return genWhile(ctx, ast);
+        return genLoop(ctx, ast);
     } else if (ast.type == "IF") {
         return genIf(ctx, ast);
     } else if (ast.type == "RETURN") {
@@ -283,11 +283,18 @@ function genSrcComment(ctx, ast) {
     ctx.code += "\n/* "+code+"  */\n";
 }
 
-function genForSrcComment(ctx, ast) {
-    const init = getSource(ctx, ast.init);
-    const condition = getSource(ctx, ast.condition);
-    const step = getSource(ctx, ast.step);
-    ctx.code += `\n/* for (${init},${condition},${step}) */\n`;
+function genLoopSrcComment(ctx, ast) {
+    if (ast.type == "FOR") {
+        const init = getSource(ctx, ast.init);
+        const condition = getSource(ctx, ast.condition);
+        const step = getSource(ctx, ast.step);
+        ctx.code += `\n/* for (${init},${condition},${step}) */\n`;
+    } else if (ast.type == "WHILE") {
+        const condition = getSource(ctx, ast.condition);
+        ctx.code += `\n/* while (${condition}) */\n`;
+    } else {
+        assert(false, "Invalid loop type: "+ ast.type);
+    }
 }
 
 function genIfSrcComment(ctx, ast) {
@@ -835,12 +842,14 @@ function leaveConditionalCode(ctx) {
     }
 }
 
-function genFor(ctx, ast) {
-    genForSrcComment(ctx, ast);
+function genLoop(ctx, ast) {
+    genLoopSrcComment(ctx, ast);
     let inLoop = false;
-    ctx.scopes.push({});
-    gen(ctx, ast.init);
-    if (ctx.error) return;
+
+    if (ast.init) {
+        gen(ctx, ast.init);
+        if (ctx.error) return;
+    }
 
     let end=false;
     let condVarRef;
@@ -878,8 +887,10 @@ function genFor(ctx, ast) {
         gen(ctx, ast.body);
         if (ctx.error) return;
 
-        gen(ctx, ast.step);
-        if (ctx.error) return;
+        if (ast.step) {
+            gen(ctx, ast.step);
+            if (ctx.error) return;
+        }
 
         const condRef2 = gen(ctx, ast.condition);
         if (ctx.error) return;
@@ -919,20 +930,6 @@ function genFor(ctx, ast) {
     ctx.scopes.pop();
 }
 
-function genWhile(ctx, ast) {
-    const condition = gen(ctx, ast.condition);
-    if (ctx.error) return;
-    const body = gen(ctx, ast.body);
-    if (ctx.error) return;
-    return `while (bigInt(${condition}).neq(bigInt(0))) {\n${body}\n}\n`;
-}
-
-function genCompute(ctx, ast) {
-    const body = gen(ctx, ast.body);
-    if (ctx.error) return;
-    return `{\n${body}\n}\n`;
-}
-
 function genIf(ctx, ast) {
     genIfSrcComment(ctx, ast);
     const condRef = gen(ctx, ast.condition);
@@ -1095,54 +1092,68 @@ function genOp(ctx, ast, op, nOps) {
     return rRef;
 }
 
-function genBAnd(ctx, ast) {
-    const a = gen(ctx, ast.values[0]);
-    if (ctx.error) return;
-    const b = gen(ctx, ast.values[1]);
-    if (ctx.error) return;
-    return `bigInt(${a}).and(bigInt(${b})).and(__MASK__)`;
-}
 
-function genAnd(ctx, ast) {
-    const a = gen(ctx, ast.values[0]);
-    if (ctx.error) return;
-    const b = gen(ctx, ast.values[1]);
+function genTerCon(ctx, ast) {
+    const condRef = gen(ctx, ast.values[0]);
     if (ctx.error) return;
-    return `((bigInt(${a}).neq(bigInt(0)) && bigInt(${b}).neq(bigInt(0))) ? bigInt(1) : bigInt(0))`;
-}
+    const cond = ctx.refs[condRef];
+    if (!utils.sameSizes(cond.sizes, [1,0])) return ctx.throwError(ast.condition, "Operation cannot be done on an array");
 
-function genOr(ctx, ast) {
-    const a = gen(ctx, ast.values[0]);
-    if (ctx.error) return;
-    const b = gen(ctx, ast.values[1]);
-    if (ctx.error) return;
-    return `((bigInt(${a}).neq(bigInt(0)) || bigInt(${b}).neq(bigInt(0))) ? bigInt(1) : bigInt(0))`;
-}
+    let oldCode;
+    if (cond.used) {
+        enterConditionalCode(ctx, ast);
 
-function genShl(ctx, ast) {
-    const a = gen(ctx, ast.values[0]);
-    if (ctx.error) return;
-    const b = gen(ctx, ast.values[1]);
-    if (ctx.error) return;
-    return `bigInt(${b}).greater(bigInt(256)) ? 0 : bigInt(${a}).shl(bigInt(${b})).and(__MASK__)`;
-}
+        const rLabel = ctx.getUniqueName("_ter");
 
-function genShr(ctx, ast) {
-    const a = gen(ctx, ast.values[0]);
-    if (ctx.error) return;
-    const b = gen(ctx, ast.values[1]);
-    if (ctx.error) return;
-    return `bigInt(${b}).greater(bigInt(256)) ? 0 : bigInt(${a}).shr(bigInt(${b})).and(__MASK__)`;
-}
+        ctx.codeHeader += `PBigInt ${rLabel};\n`;
+        ctx.code += `if (ctx->field->isTrue(${cond.label})) {\n`;
 
-function genTerCon(ctx, ast) {
-    const a = gen(ctx, ast.values[0]);
-    if (ctx.error) return;
-    const b = gen(ctx, ast.values[1]);
-    if (ctx.error) return;
-    const c = gen(ctx, ast.values[2]);
-    if (ctx.error) return;
-    return `bigInt(${a}).neq(bigInt(0)) ? (${b}) : (${c})`;
+        oldCode = ctx.code;
+        ctx.code = "";
+
+        const thenRef = gen(ctx, ast.values[1]);
+        if (ctx.error) return;
+        const then = ctx.refs[thenRef];
+
+        ctx.code = oldCode + utils.ident(ctx.code);
+
+        ctx.code += `${rLabel} = ${then.label};\n`;
+
+        ctx.code += "} else {\n";
+
+        oldCode = ctx.code;
+        ctx.code = "";
+        const elseRef = gen(ctx, ast.values[2]);
+        if (ctx.error) return;
+        const els = ctx.refs[elseRef];
+
+        ctx.code = oldCode + utils.ident(ctx.code);
+
+        ctx.code += `${rLabel} = ${els.label};\n`;
+
+        ctx.code += "}\n";
+
+
+        if (!utils.sameSizes(then.sizes, els.sizes)) return ctx.throwError(ast, "Ternary op must return the same sizes");
+
+        const refId = ctx.refs.length;
+        ctx.refs.push({
+            type: "BIGINT",
+            sizes: then.sizes,
+            used: true,
+            label: rLabel
+        });
+
+        return refId;
+
+    } else {
+        if (!utils.isDefined(cond.value)) return ctx.throwError(ast, "condition value not assigned");
+        if (!cond.value[0].isZero()) {
+            return gen(ctx, ast.values[1]);
+        } else {
+            return gen(ctx, ast.values[2]);
+        }
+    }
 }
 
 function genInclude(ctx, ast) {
diff --git a/src/c_tester.js b/src/c_tester.js
index e8dc1d8..1f85b58 100644
--- a/src/c_tester.js
+++ b/src/c_tester.js
@@ -108,6 +108,9 @@ class CTester {
                     checkObject(prefix + "."+k, eOut[k]);
                 }
             } else {
+                if (typeof self.symbols[prefix] == "undefined") {
+                    assert(false, "Output variable not defined: "+ prefix);
+                }
                 const ba = bigInt(actualOut[self.symbols[prefix].idxWit]).toString();
                 const be = bigInt(eOut).toString();
                 assert.strictEqual(ba, be, prefix);
diff --git a/src/zqfield.js b/src/zqfield.js
index 86f64c1..565788f 100644
--- a/src/zqfield.js
+++ b/src/zqfield.js
@@ -58,6 +58,7 @@ module.exports = class ZqField {
     }
 
     div(a, b) {
+        assert(!b.isZero(), "Division by zero");
         return a.mul(b.modInv(this.p)).mod(this.p);
     }
 
diff --git a/test/basiccases.js b/test/basiccases.js
index b79de94..3baeecf 100644
--- a/test/basiccases.js
+++ b/test/basiccases.js
@@ -92,6 +92,25 @@ describe("basic cases", function () {
             ]
         );
     });
+    it("while unrolled", async () => {
+        await doTest(
+            "whileunrolled.circom",
+            [
+                [{in: 0}, {out: [0,1,2]}],
+                [{in: 10}, {out: [10, 11, 12]}],
+                [{in: __P__.minus(2)}, {out: [__P__.minus(2), __P__.minus(1), 0]}],
+            ]
+        );
+    });
+    it("while rolled", async () => {
+        await doTest(
+            "whilerolled.circom",
+            [
+                [{in: 0}, {out: 0}],
+                [{in: 10}, {out: 10}],
+            ]
+        );
+    });
     it("function1", async () => {
         await doTest(
             "function1.circom",
@@ -246,4 +265,26 @@ describe("basic cases", function () {
             ]
         );
     });
+    it("Conditional Ternary operator", async () => {
+        await doTest(
+            "condternary.circom",
+            [
+                [{in: 0}, {out: 21}],
+                [{in: 1}, {out:  1}],
+                [{in: 2}, {out: 23}],
+                [{in:-1}, {out: 20}],
+            ]
+        );
+    });
+    it("Compute block", async () => {
+        await doTest(
+            "compute.circom",
+            [
+                [{x: 1}, {y:  7}],
+                [{x: 2}, {y:  7}],
+                [{x: 3}, {y: 11}],
+                [{x:-1}, {y: -5}],
+            ]
+        );
+    });
 });
diff --git a/test/circuits/condternary.circom b/test/circuits/condternary.circom
new file mode 100644
index 0000000..476783f
--- /dev/null
+++ b/test/circuits/condternary.circom
@@ -0,0 +1,15 @@
+template CondTernary() {
+    signal input in;
+    signal output out;
+
+    var a = 3;
+    var b = a==3 ? 1 : 2;      // b is 1
+    var c = a!=3 ? 10 : 20;      // c is 20
+    var d = b+c;   // d is 21
+
+
+    out <-- ((in & 1) != 1) ? in + d : in;  // Add 21 if in is pair
+
+}
+
+component main = CondTernary()
diff --git a/test/circuits/whilerolled.circom b/test/circuits/whilerolled.circom
new file mode 100644
index 0000000..e8e7d6e
--- /dev/null
+++ b/test/circuits/whilerolled.circom
@@ -0,0 +1,16 @@
+template WhileRolled() {
+    signal input in;
+    signal output out;
+
+    var acc = 0;
+
+    var i=0;
+    while (i<in) {
+        acc = acc + 1;
+        i++
+    }
+
+    out <== acc;
+}
+
+component main = WhileRolled();
diff --git a/test/circuits/whileunrolled.circom b/test/circuits/whileunrolled.circom
new file mode 100644
index 0000000..2a15d3d
--- /dev/null
+++ b/test/circuits/whileunrolled.circom
@@ -0,0 +1,12 @@
+template WhileUnrolled(n) {
+    signal input in;
+    signal output out[n];
+
+    var i=0;
+    while (i<n) {
+        out[i] <== in + i;
+        i++;
+    }
+}
+
+component main = WhileUnrolled(3);