initial import of the C runtime

src/runtime/c/gu/variant.c

@@ -0,0 +1,100 @@
+/* 
+ * Copyright 2010 University of Helsinki.
+ *   
+ * This file is part of libgu.
+ * 
+ * Libgu is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ * 
+ * Libgu is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+ * License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with libgu. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "variant.h"
+#include "bits.h"
+
+enum {
+	GU_VARIANT_ALIGNMENT = sizeof(uintptr_t)
+};
+
+void* 
+gu_alloc_variant(uint8_t tag, size_t size, 
+		 size_t align, GuVariant* variant_out, GuPool* pool)
+{
+	align = gu_max(align, GU_VARIANT_ALIGNMENT);
+	if (((size_t)tag) > GU_VARIANT_ALIGNMENT - 2) {
+		uint8_t* alloc = gu_malloc_aligned(pool, align + size, align);
+		alloc[align - 1] = tag;
+		void* p = &alloc[align];
+		variant_out->p = (uintptr_t)p;
+		return p;
+	}
+	void* p = gu_malloc_aligned(pool, size, align);
+	variant_out->p = ((uintptr_t)p) | (tag + 1);
+	return p;
+}
+
+GuVariant 
+gu_make_variant(uint8_t tag, size_t size, size_t align, const void* init,
+		GuPool* pool)
+{
+	GuVariant v;
+	void* data = gu_alloc_variant(tag, size, align, &v, pool);
+	memcpy(data, init, size);
+	return v;
+}
+
+int
+gu_variant_tag(GuVariant variant)
+{
+	if (gu_variant_is_null(variant)) {
+		return GU_VARIANT_NULL;
+	}
+	int u = variant.p % GU_VARIANT_ALIGNMENT;
+	if (u == 0) {
+		uint8_t* mem = (uint8_t*)variant.p;
+		return mem[-1];
+	}
+	return u - 1;
+}
+
+void*
+gu_variant_data(GuVariant variant)
+{
+	if (gu_variant_is_null(variant)) {
+		return NULL;
+	}
+	return (void*)gu_align_backward(variant.p, GU_VARIANT_ALIGNMENT);
+}
+
+GuVariantInfo gu_variant_open(GuVariant variant)
+{
+	GuVariantInfo info = {
+		.tag = gu_variant_tag(variant),
+		.data = gu_variant_data(variant)
+	};
+	return info;
+}
+
+int 
+gu_variant_intval(GuVariant variant)
+{
+	int u = variant.p % GU_VARIANT_ALIGNMENT;
+	if (u == 0) {
+		int* mem = (int*)variant.p;
+		return *mem;
+	}
+	return (variant.p / GU_VARIANT_ALIGNMENT);
+}
+
+const GuVariant gu_null_variant = { (GuWord) NULL };
+
+GU_DEFINE_KIND(GuVariant, repr);
+GU_DEFINE_KIND(GuVariantAsPtr, repr);