Implement log2 and log functions in math.tact

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- `log2` and `log` math functions in stdlib: PR [#166](https://github.com/tact-lang/tact/pull/166)
+
 ### Changed
 
 ### Fixed

src/generator/writers/__snapshots__/writeSerialization.spec.ts.snap

@@ -2972,6 +2972,38 @@ return b.end_cell().begin_parse();",
     "name": "__tact_float_to_string",
     "signature": "slice __tact_float_to_string(int src, int digits)",
   },
+  {
+    "code": {
+      "code": "asm "UBITSIZE DEC"",
+      "kind": "asm",
+    },
+    "comment": null,
+    "context": "stdlib",
+    "depends": Set {},
+    "flags": Set {},
+    "name": "__tact_log2",
+    "signature": "int __tact_log2(int num)",
+  },
+  {
+    "code": {
+      "code": "if (num < base) {
+    return 0;
+}
+int result = 0;
+while (num >= base) {
+    num /= base;
+    result += 1;
+}
+return result;",
+      "kind": "generic",
+    },
+    "comment": null,
+    "context": "stdlib",
+    "depends": Set {},
+    "flags": Set {},
+    "name": "__tact_log",
+    "signature": "int __tact_log(int num, int base)",
+  },
   {
     "code": {
       "code": "var (v'a, v'b, v'c, v'd, v'e, v'f, v'g) = v;
@@ -6795,6 +6827,38 @@ return b.end_cell().begin_parse();",
     "name": "__tact_float_to_string",
     "signature": "slice __tact_float_to_string(int src, int digits)",
   },
+  {
+    "code": {
+      "code": "asm "UBITSIZE DEC"",
+      "kind": "asm",
+    },
+    "comment": null,
+    "context": "stdlib",
+    "depends": Set {},
+    "flags": Set {},
+    "name": "__tact_log2",
+    "signature": "int __tact_log2(int num)",
+  },
+  {
+    "code": {
+      "code": "if (num < base) {
+    return 0;
+}
+int result = 0;
+while (num >= base) {
+    num /= base;
+    result += 1;
+}
+return result;",
+      "kind": "generic",
+    },
+    "comment": null,
+    "context": "stdlib",
+    "depends": Set {},
+    "flags": Set {},
+    "name": "__tact_log",
+    "signature": "int __tact_log(int num, int base)",
+  },
   {
     "code": {
       "code": "var (v'a, v'b, v'c, v'd, v'e, v'f, v'g) = v;
@@ -10618,6 +10682,38 @@ return b.end_cell().begin_parse();",
     "name": "__tact_float_to_string",
     "signature": "slice __tact_float_to_string(int src, int digits)",
   },
+  {
+    "code": {
+      "code": "asm "UBITSIZE DEC"",
+      "kind": "asm",
+    },
+    "comment": null,
+    "context": "stdlib",
+    "depends": Set {},
+    "flags": Set {},
+    "name": "__tact_log2",
+    "signature": "int __tact_log2(int num)",
+  },
+  {
+    "code": {
+      "code": "if (num < base) {
+    return 0;
+}
+int result = 0;
+while (num >= base) {
+    num /= base;
+    result += 1;
+}
+return result;",
+      "kind": "generic",
+    },
+    "comment": null,
+    "context": "stdlib",
+    "depends": Set {},
+    "flags": Set {},
+    "name": "__tact_log",
+    "signature": "int __tact_log(int num, int base)",
+  },
   {
     "code": {
       "code": "var (v'a, v'b, v'c, v'd, v'e, v'f, v'g, v'h) = v;

src/generator/writers/writeStdlib.ts

@@ -1223,4 +1223,28 @@ export function writeStdlib(ctx: WriterContext) {
             `);
         });
     });
+
+    ctx.fun(`__tact_log2`, () => {
+        ctx.signature(`int __tact_log2(int num)`);
+        ctx.context('stdlib');
+        ctx.asm(`asm "UBITSIZE DEC"`);
+    });
+
+    ctx.fun(`__tact_log`, () => {
+        ctx.signature(`int __tact_log(int num, int base)`);
+        ctx.context('stdlib');
+        ctx.body(() => {
+            ctx.write(`
+                if (num < base) {
+                    return 0;
+                }
+                int result = 0;
+                while (num >= base) {
+                    num /= base;
+                    result += 1;
+                }
+                return result;
+            `);
+        });
+    });
 }

src/imports/stdlib.ts

@@ -183,7 +183,9 @@ files['std/math.tact'] =
     'CmlubGluZSBmdW4gcmFuZG9tSW50KCk6IEludCB7CiAgICBuYXRpdmVQcmVwYXJlUmFuZG9tKCk7CiAgICByZXR1cm4gbmF0aXZlUmFuZG9tKCk7Cn0KCmlubGluZSBm' +
     'dW4gcmFuZG9tKG1pbjogSW50LCBtYXg6IEludCk6IEludCB7CiAgICBuYXRpdmVQcmVwYXJlUmFuZG9tKCk7CiAgICByZXR1cm4gbWluICsgbmF0aXZlUmFuZG9tSW50' +
     'ZXJ2YWwobWF4IC0gbWluKTsKfQoKLy8gTWF0aAoKQG5hbWUobWluKQpuYXRpdmUgbWluKHg6IEludCwgeTogSW50KTogSW50OwoKQG5hbWUobWF4KQpuYXRpdmUgbWF4' +
-    'KHg6IEludCwgeTogSW50KTogSW50OwoKQG5hbWUoYWJzKQpuYXRpdmUgYWJzKHg6IEludCk6IEludDsKCkBuYW1lKG5vdykKbmF0aXZlIG5vdygpOiBJbnQ7';
+    'KHg6IEludCwgeTogSW50KTogSW50OwoKQG5hbWUoYWJzKQpuYXRpdmUgYWJzKHg6IEludCk6IEludDsKCkBuYW1lKG5vdykKbmF0aXZlIG5vdygpOiBJbnQ7CgpAbmFt' +
+    'ZShfX3RhY3RfbG9nMikKbmF0aXZlIGxvZzIobnVtOiBJbnQpOiBJbnQ7CgpAbmFtZShfX3RhY3RfbG9nKQpuYXRpdmUgbG9nKG51bTogSW50LCBiYXNlOiBJbnQpOiBJ' +
+    'bnQ7';
 files['std/primitives.tact'] =
     'cHJpbWl0aXZlIEludDsKcHJpbWl0aXZlIEJvb2w7CnByaW1pdGl2ZSBCdWlsZGVyOwpwcmltaXRpdmUgU2xpY2U7CnByaW1pdGl2ZSBDZWxsOwpwcmltaXRpdmUgQWRk' +
     'cmVzczsKcHJpbWl0aXZlIFN0cmluZzsKcHJpbWl0aXZlIFN0cmluZ0J1aWxkZXI7';

src/test/feature-math.spec.ts

@@ -7,8 +7,7 @@ describe('feature-math', () => {
     beforeEach(() => {
         __DANGER_resetNodeId();
     });
-    it('should perform basic math operations correctly', async () => {
-
+    it('should perform math operations correctly', async () => {
         // Init
         const system = await ContractSystem.create();
         const treasure = system.treasure('treasure');
@@ -25,11 +24,15 @@ describe('feature-math', () => {
             .storeBit(1)
             .storeRef(beginCell().storeBit(1).endCell())
             .endCell();
-        const stringA = "foo";
-        const stringB = "bar";
+        const stringA = 'foo';
+        const stringB = 'bar';
         const dictA = Dictionary.empty<bigint, bigint>().set(0n, 0n);
         const dictB = Dictionary.empty<bigint, bigint>().set(0n, 2n);
-        await contract.send(treasure, { value: toNano('10') }, { $$type: 'Deploy', queryId: 0n });
+        await contract.send(
+            treasure,
+            { value: toNano('10') },
+            { $$type: 'Deploy', queryId: 0n }
+        );
         await system.run();
 
         // Tests
@@ -335,5 +338,53 @@ describe('feature-math', () => {
         expect(await contract.getCompare28(dictA, dictB)).toBe(true);
         expect(await contract.getCompare28(dictB, dictA)).toBe(true);
         expect(await contract.getCompare28(dictA, dictA)).toBe(false);
+
+        // Test advanced math operations
+        for (let num = 1n; num <= 100n; num++) {
+            expect(await contract.getLog2(num)).toBe(
+                BigInt(Math.floor(Math.log2(Number(num))))
+            );
+        }
+
+        for (let num = 1n; num <= 10n; num++) {
+            for (let base = 2n; base <= 10; base++) {
+                const logarithm = BigInt(
+                    Math.floor(Math.log2(Number(num)) / Math.log2(Number(base)))
+                );
+                expect(await contract.getLog(num, base)).toBe(logarithm);
+            }
+        }
+
+        expect(await contract.getLog2(0n)).toBe(-1n);
+        expect(await contract.getLog(0n, 2n)).toBe(0n);
+
+        const maxint = 2n ** 256n - 1n;
+
+        for (let num = maxint - 100n; num <= maxint; num++) {
+            expect(await contract.getLog2(num)).toBe(255n);
+        }
+
+        for (let num = maxint - 10n; num <= maxint; num++) {
+            for (let base = 2; base <= 10; base++) {
+                expect(await contract.getLog(num, BigInt(base))).toBe(
+                    BigInt(num.toString(base).length - 1)
+                );
+            }
+        }
+
+        for (let num = maxint / 2n - 50n; num <= maxint / 2n; num++) {
+            expect(await contract.getLog2(num)).toBe(254n);
+        }
+        for (let num = maxint / 2n + 1n; num <= maxint / 2n + 50n; num++) {
+            expect(await contract.getLog2(num)).toBe(255n);
+        }
+
+        for (let num = maxint / 2n - 5n; num <= maxint / 2n + 5n; num++) {
+            for (let base = 2; base <= 10; base++) {
+                expect(await contract.getLog(num, BigInt(base))).toBe(
+                    BigInt(num.toString(base).length - 1)
+                );
+            }
+        }
     });
-});
+});

src/test/features/math.tact

@@ -295,4 +295,16 @@ contract MathTester with Deployable {
     get fun isNotNull3(cell: Cell?): Bool {
         return cell != null;
     }
+
+    //
+    // Advanced Math Operations
+    //
+
+    get fun log2(num: Int): Int {
+        return log2(num);
+    }
+
+    get fun log(num: Int, base: Int): Int {
+        return log(num, base);
+    }
 }

stdlib/std/math.tact

@@ -39,4 +39,10 @@ native max(x: Int, y: Int): Int;
 native abs(x: Int): Int;
 
 @name(now)
-native now(): Int;
+native now(): Int;
+
+@name(__tact_log2)
+native log2(num: Int): Int;
+
+@name(__tact_log)
+native log(num: Int, base: Int): Int;