llparse/lib/implementation/c/code/mul-add.js

Compile incremental parsers to C code

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.MulAdd = void 0;
const assert = require("assert");
const constants_1 = require("../constants");
const field_1 = require("./field");
class MulAdd extends field_1.Field {
    doBuild(ctx, out) {
        const options = this.ref.options;
        const ty = ctx.getFieldType(this.ref.field);
        let field = this.field(ctx);
        if (options.signed) {
            assert(constants_1.SIGNED_TYPES.has(ty), `Unexpected mulAdd type "${ty}"`);
            const targetTy = constants_1.SIGNED_TYPES.get(ty);
            out.push(`${targetTy}* field = (${targetTy}*) &${field};`);
            field = '(*field)';
        }
        const match = ctx.matchVar();
        const limits = options.signed ? constants_1.SIGNED_LIMITS : constants_1.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;');
    }
}
exports.MulAdd = MulAdd;
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