From 2df2bcf9082c4e020eac0095c354444382c3107c Mon Sep 17 00:00:00 2001
From: Dmitry Volyntsev <xeioexception@gmail.com>
Date: Wed, 8 May 2024 14:38:34 -0700
Subject: [PATCH] Add `JS_GetTypedArray()`

---
 quickjs.c | 26 ++++++++++++++++++++++++++
 quickjs.h | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/quickjs.c b/quickjs.c
index f000ff7..bf5989d 100644
--- a/quickjs.c
+++ b/quickjs.c
@@ -53439,6 +53439,32 @@ JSValue JS_NewTypedArray(JSContext *ctx, int argc, JSValueConst *argv,
                                       JS_CLASS_UINT8C_ARRAY + type);
 }
 
+/* Return value is -1 for proxy errors, 0 if `obj` is not a typed array,
+   1 if it is a typed array.
+   The structure pointed to by `desc` is filled on success unless `desc`
+   is a null pointer. */
+int JS_GetTypedArray(JSContext *ctx, JSValueConst obj,
+                     JSTypedArrayDescriptor *desc)
+{
+    int class_id;
+    JSObject *p;
+
+    if (js_resolve_proxy(ctx, &obj, TRUE))
+        return -1;
+    if (JS_VALUE_GET_TAG(obj) != JS_TAG_OBJECT)
+        return 0;
+    p = JS_VALUE_GET_OBJ(obj);
+    class_id = p->class_id;
+    if (class_id < JS_CLASS_UINT8C_ARRAY || class_id > JS_CLASS_FLOAT64_ARRAY)
+        return 0;
+    if (desc) {
+        desc->type = JS_TYPED_ARRAY_UINT8C + (class_id - JS_CLASS_UINT8C_ARRAY);
+        desc->length = p->u.typed_array->length;
+        desc->data = p->u.array.u.ptr;
+    }
+    return 1;
+}
+
 /* Return the buffer associated to the typed array or an exception if
    it is not a typed array or if the buffer is detached. pbyte_offset,
    pbyte_length or pbytes_per_element can be NULL. */
diff --git a/quickjs.h b/quickjs.h
index edc7b47..84a7e0b 100644
--- a/quickjs.h
+++ b/quickjs.h
@@ -845,8 +845,40 @@ typedef enum JSTypedArrayEnum {
     JS_TYPED_ARRAY_FLOAT64,
 } JSTypedArrayEnum;
 
+static inline int JS_BytesPerElement(JSTypedArrayEnum type)
+{
+    switch (type) {
+    case JS_TYPED_ARRAY_UINT8C:
+    case JS_TYPED_ARRAY_INT8:
+    case JS_TYPED_ARRAY_UINT8:
+        return 1;
+    case JS_TYPED_ARRAY_INT16:
+    case JS_TYPED_ARRAY_UINT16:
+        return 2;
+    case JS_TYPED_ARRAY_INT32:
+    case JS_TYPED_ARRAY_UINT32:
+    case JS_TYPED_ARRAY_FLOAT32:
+        return 4;
+    default:
+        return 8;
+    }
+}
+
 JSValue JS_NewTypedArray(JSContext *ctx, int argc, JSValueConst *argv,
                          JSTypedArrayEnum array_type);
+
+typedef struct JSTypedArrayDescriptor {
+    JSTypedArrayEnum type;
+    size_t length;
+    void *data;
+} JSTypedArrayDescriptor;
+
+/* Return value is -1 for proxy errors, 0 if `obj` is not a typed array,
+   1 if it is a typed array.
+   The structure pointed to by `desc` is filled on success unless `desc`
+   is a null pointer. */
+int JS_GetTypedArray(JSContext *ctx, JSValueConst obj,
+                     JSTypedArrayDescriptor *desc);
 JSValue JS_GetTypedArrayBuffer(JSContext *ctx, JSValueConst obj,
                                size_t *pbyte_offset,
                                size_t *pbyte_length,