Add setBytes method to DataView

- Writes multiple bytes at once
- Bytes can be either an array or string

ext/arraybuffer/dataview.c

@@ -434,6 +434,37 @@ t_dv_setu32(VALUE self, VALUE index, VALUE value) {
   return self;
 }
 
+static VALUE
+t_dv_setbytes(VALUE self, VALUE index, VALUE bytes) {
+  DECLAREDV(self); DECLARENCHECKIDX(index); DECLAREBB(dv->bb_obj);
+  unsigned int idx0 = dv->offset + (unsigned int)idx;
+  CHECKBOUNDSBB(idx0);
+
+  if (RB_TYPE_P(bytes, T_ARRAY)) {
+    const unsigned int length = (unsigned int)rb_array_len(bytes);
+    const VALUE* items = rb_array_const_ptr(bytes);
+    CHECKBOUNDSBB(idx0 + length);
+
+    for (unsigned int i = 0; i < length; i++) {
+      int num = NUM2INT(items[i]);
+      ADJUSTBOUNDS(num, 0xFF);
+      bb->ptr[idx0 + i] = (unsigned char)num;
+    }
+  } else if (RB_TYPE_P(bytes, T_STRING)) {
+    const char *str_ptr = RSTRING_PTR(bytes);
+    const unsigned int length = (unsigned int)RSTRING_LEN(bytes);
+    CHECKBOUNDSBB(idx0 + length);
+
+    for (unsigned int i = 0; i < length; i++) {
+      bb->ptr[idx0 + i] = (unsigned char)str_ptr[i];
+    }
+  } else {
+    rb_raise(rb_eArgError, "Invalid type");
+  }
+
+  return self;
+}
+
 void
 Init_dataview() {
   idEndianess = rb_intern("endianess");
@@ -455,6 +486,7 @@ Init_dataview() {
   rb_define_method(cDataView, "setU16", t_dv_setu16, 2);
   rb_define_method(cDataView, "setU24", t_dv_setu24, 2);
   rb_define_method(cDataView, "setU32", t_dv_setu32, 2);
+  rb_define_method(cDataView, "setBytes", t_dv_setbytes, 2);
 
   rb_define_method(cDataView, "endianess", t_dv_endianess, 0);
   rb_define_method(cDataView, "offset=", t_dv_setoffset, 1);

spec/dataview_spec.rb

@@ -210,6 +210,35 @@
     end
   end
 
+  describe "setBytes" do
+    let(:dv) { described_class.new(buffer, 1) }
+    let(:new_bytes) { [40, 0, 13, 25, 250, 127, 128] }
+    let(:expected_bytes) { [1, 40, 0, 13, 25, 250, 127, 128, 99, 192, 32, 12, 0, 49] }
+
+    context "when argument is an array" do
+      it "sets the bytes" do
+        dv.setBytes(0, new_bytes)
+        expect(buffer.bytes.split('').map(&:ord)).to eq(expected_bytes)
+      end
+    end
+
+    context "when argument is a string" do
+      it "sets the bytes" do
+        dv.setBytes(0, new_bytes.map(&:chr).join)
+        expect(buffer.bytes.split('').map(&:ord)).to eq(expected_bytes)
+      end
+    end
+
+    context "when argument is an utf-8 string" do
+      let(:expected_bytes) { [1, 233, 139, 184, 105, 27, 175, 88, 99, 192, 32, 12, 0, 49] }
+
+      it "sets the bytes" do
+        dv.setBytes(0, "鋸i")
+        expect(buffer.bytes.split('').map(&:ord)).to eq(expected_bytes)
+      end
+    end
+  end
+
   shared_examples "offset out of bounds" do
     context "when offset is greater than the underlying buffer" do
       let(:offset) { 1000 }