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#include "variant.h"
#include "bits.h"
enum {
GU_VARIANT_ALIGNMENT = sizeof(uintptr_t)
};
GU_API 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 = (uintptr_t)p;
return p;
}
void* p = gu_malloc_aligned(pool, size, align);
*variant_out = ((uintptr_t)p) | (tag + 1);
return p;
}
GU_API 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;
}
GU_API int
gu_variant_tag(GuVariant variant)
{
if (gu_variant_is_null(variant)) {
return GU_VARIANT_NULL;
}
int u = variant % GU_VARIANT_ALIGNMENT;
if (u == 0) {
uint8_t* mem = (uint8_t*)variant;
return mem[-1];
}
return u - 1;
}
GU_API void*
gu_variant_data(GuVariant variant)
{
if (gu_variant_is_null(variant)) {
return NULL;
}
return (void*)gu_align_backward(variant, GU_VARIANT_ALIGNMENT);
}
GU_API GuVariantInfo
gu_variant_open(GuVariant variant)
{
GuVariantInfo info = {
.tag = gu_variant_tag(variant),
.data = gu_variant_data(variant)
};
return info;
}
GU_API GuVariant
gu_variant_close(GuVariantInfo info)
{
GuVariant variant;
if (((size_t)info.tag) > GU_VARIANT_ALIGNMENT - 2) {
variant = (uintptr_t)info.data;
assert(gu_variant_tag(variant) == info.tag);
} else {
variant = ((uintptr_t)info.data) | (info.tag + 1);
}
return variant;
}
GU_API int
gu_variant_intval(GuVariant variant)
{
int u = variant % GU_VARIANT_ALIGNMENT;
if (u == 0) {
int* mem = (int*)variant;
return *mem;
}
return (variant / GU_VARIANT_ALIGNMENT);
}
GU_API const GuVariant gu_null_variant = { (GuWord) NULL };
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