1 files changed, 67 insertions, 0 deletions
diff --git a/llparse/src/implementation/c/code/mul-add.ts b/llparse/src/implementation/c/code/mul-add.ts
new file mode 100644
index 0000000..fd5ce8c
--- /dev/null
+++ b/llparse/src/implementation/c/code/mul-add.ts
@@ -0,0 +1,67 @@
+import * as assert from 'assert';
+import * as frontend from 'llparse-frontend';
+
+import { Compilation } from '../compilation';
+import { SIGNED_LIMITS, UNSIGNED_LIMITS, SIGNED_TYPES } from '../constants';
+import { Field } from './field';
+
+export class MulAdd extends Field<frontend.code.MulAdd> {
+  protected doBuild(ctx: Compilation, out: string[]): void {
+    const options = this.ref.options;
+    const ty = ctx.getFieldType(this.ref.field);
+
+    let field = this.field(ctx);
+    if (options.signed) {
+      assert(SIGNED_TYPES.has(ty), `Unexpected mulAdd type "${ty}"`);
+      const targetTy = SIGNED_TYPES.get(ty)!;
+      out.push(`${targetTy}* field = (${targetTy}*) &${field};`);
+      field = '(*field)';
+    }
+
+    const match = ctx.matchVar();
+
+    const limits = options.signed ? SIGNED_LIMITS : UNSIGNED_LIMITS;
+    assert(limits.has(ty), `Unexpected mulAdd type "${ty}"`);
+    const [ min, max ] = limits.get(ty)!;
+
+    const mulMax = `${max} / ${options.base}`;
+    const mulMin = `${min} / ${options.base}`;
+
+    out.push('/* Multiplication overflow */');
+    out.push(`if (${field} > ${mulMax}) {`);
+    out.push('  return 1;');
+    out.push('}');
+    if (options.signed) {
+      out.push(`if (${field} < ${mulMin}) {`);
+      out.push('  return 1;');
+      out.push('}');
+    }
+    out.push('');
+
+    out.push(`${field} *= ${options.base};`);
+    out.push('');
+
+    out.push('/* Addition overflow */');
+    out.push(`if (${match} >= 0) {`);
+    out.push(`  if (${field} > ${max} - ${match}) {`);
+    out.push('    return 1;');
+    out.push('  }');
+    out.push('} else {');
+    out.push(`  if (${field} < ${min} - ${match}) {`);
+    out.push('    return 1;');
+    out.push('  }');
+    out.push('}');
+
+    out.push(`${field} += ${match};`);
+
+    if (options.max !== undefined) {
+      out.push('');
+      out.push('/* Enforce maximum */');
+      out.push(`if (${field} > ${options.max}) {`);
+      out.push('  return 1;');
+      out.push('}');
+    }
+
+    out.push('return 0;');
+  }
+}