builtins: add Porffor.allocateBytes

based off #56

Co-Authored-By: Bob Varioa <[email protected]>

compiler/builtins.js

@@ -1140,5 +1140,50 @@ export const BuiltinFuncs = function() {
     ]
   };
 
+  this.__Porffor_allocateBytes = {
+    params: [ Valtype.i32 ],
+    locals: [],
+    globals: [ Valtype.i32, Valtype.i32 ],
+    globalNames: [ 'currentPtr', 'bytesWritten' ],
+    globalInits: [ 0, pageSize ], // init to pageSize so we always allocate on first call
+    returns: [ Valtype.i32 ],
+    returnType: TYPES.number,
+    wasm: [
+      // bytesWritten += bytesToAllocate
+      [ Opcodes.local_get, 0 ],
+      [ Opcodes.global_get, 1 ],
+      [ Opcodes.i32_add ],
+      [ Opcodes.global_set, 1 ],
+
+      // if bytesWritten >= pageSize:
+      [ Opcodes.global_get, 1 ],
+      ...number(pageSize, Valtype.i32),
+      [ Opcodes.i32_ge_s ],
+      [ Opcodes.if, Valtype.i32 ],
+        // bytesWritten = 0
+        [ Opcodes.local_get, 0 ],
+        [ Opcodes.global_set, 1 ],
+
+        // grow memory by 1 page
+        ...number(1, Valtype.i32),
+        [ Opcodes.memory_grow, 0x00 ],
+
+        // currentPtr = old page count * pageSize
+        ...number(pageSize, Valtype.i32),
+        [ Opcodes.i32_mul ],
+        [ Opcodes.global_set, 0 ],
+      [ Opcodes.else ],
+        // else, currentPtr += bytesToAllocate
+        [ Opcodes.global_get, 0 ],
+        [ Opcodes.local_get, 0 ],
+        [ Opcodes.i32_add ],
+        [ Opcodes.global_set, 0 ]
+      [ Opcodes.end ],
+
+      // return currentPtr
+      [ Opcodes.global_get, 0 ]
+    ]
+  };
+
   GeneratedBuiltins.BuiltinFuncs.call(this);
 };

package.json

@@ -1,7 +1,7 @@
 {
   "name": "porffor",
   "description": "a basic experimental wip aot optimizing js -> wasm engine/compiler/runtime in js",
-  "version": "0.18.10+c0227b1a9",
+  "version": "0.18.11+3744bea72",
   "author": "CanadaHonk",
   "license": "MIT",
   "scripts": {},

runner/index.js

@@ -1,6 +1,6 @@
 #!/usr/bin/env node
 import fs from 'node:fs';
-globalThis.version = '0.18.10+c0227b1a9';
+globalThis.version = '0.18.11+3744bea72';
 
 // deno compat
 if (typeof process === 'undefined' && typeof Deno !== 'undefined') {