mirror of
https://github.com/janet-lang/janet
synced 2024-11-20 07:34:49 +00:00
266 lines
9.2 KiB
C
266 lines
9.2 KiB
C
#include <dst/dst.h>
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#include <stdbool.h>
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#include <math.h>
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#include "unit.h"
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/* Required interface for DstValue */
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/* wrap and unwrap for all types */
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/* Get type quickly */
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/* Check against type quickly */
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/* Small footprint */
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/* 64 bit integer support undecided */
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/* dst_type(x)
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* dst_checktype(x, t)
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* dst_wrap_##TYPE(x)
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* dst_unwrap_##TYPE(x)
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* dst_truthy(x)
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* dst_memclear(p, n) - clear memory for hash tables to nils
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* dst_isnan(x) - check if value is nan
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*/
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typedef union dst_t dst_t;
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union dst_t {
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uint64_t u64;
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int64_t i64;
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void *pointer;
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double real;
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};
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/* dst_t */
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/* This representation uses 48 bit pointers. The trade off vs. the LuaJIT style
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* 47 bit payload representaion is that the type bits are no long contiguous. Type
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* checking can still be fast, but typewise polymorphism takes a bit longer. However,
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* hopefully we can avoid some annoying problems that occur when trying to use 47 bit pointers
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* in a 48 bit address space (Linux on ARM) */
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enum dst_t_tag {
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DST_T_NIL,
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DST_T_TRUE,
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DST_T_FALSE,
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DST_T_INTEGER,
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DST_T_FIBER,
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DST_T_STRUCT,
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DST_T_TUPLE,
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DST_T_ARRAY,
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DST_T_BUFFER,
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DST_T_TABLE,
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DST_T_USERDATA,
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DST_T_FUNCTION,
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DST_T_CFUNCTION,
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DST_T_STRING,
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DST_T_SYMBOL,
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DST_T_REAL
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};
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/* |.......Tag.......|.......................Payload..................| */
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/* Non-double: t|11111111111|1ttt|xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx */
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/* Types of NIL, TRUE, and FALSE must have payload set to all 1s. */
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/* Double (no NaNs): x xxxxxxxxxxx xxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx */
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/* A simple scheme for nan boxed values */
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/* normal doubles, denormalized doubles, and infinities are doubles */
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/* Quiet nan is nil. Sign bit should be 0. */
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#define DST_NANBOX_TYPEBITS 0x0007000000000000lu
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#ifdef DST_64
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#define DST_NANBOX_POINTERBITS 0x0000FFFFFFFFFFFFlu
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#else
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#define DST_NANBOX_POINTERBITS 0x00000000FFFFFFFFlu
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#endif
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#define DST_NANBOX_QUIET_BIT 0x0008000000000000lu
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#define dst_nanbox_isreal(x) (!isnan((x).real))
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#define dst_nanbox_tag(type) \
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((((uint64_t)(type) & 0x8) << 12) | 0x7FF8 | (type))
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#define dst_nanbox_tagbits(x) \
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((x).u64 & 0xFFFF000000000000lu)
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#define dst_nanbox_payloadbits(x) \
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((x).u64 & 0x0000FFFFFFFFFFFFlu)
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#define dst_nanbox_type(x) \
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(dst_nanbox_isreal(x) \
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? DST_T_REAL \
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: (((x).u64 & DST_NANBOX_TYPEBITS) >> 48) | (((x).u64 >> 60) & 0x8))
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#define dst_nanbox_checktype(x, t) \
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(((t) == DST_T_REAL) \
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? dst_nanbox_isreal(x) \
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: (!dst_nanbox_isreal(x) && (((x).u64 >> 48) == dst_nanbox_tag(t))))
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static inline void *dst_nanbox_to_pointer(dst_t x) {
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/* We need to do this shift to keep the higher bits of the pointer
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* the same as bit 47 as required by the x86 architecture. We may save
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* an instruction if we do x.u64 & DST_NANBOX_POINTERBITS, but this 0s
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* th high bits. */
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x.i64 = (x.i64 << 16) >> 16;
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return x.pointer;
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}
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static inline dst_t dst_nanbox_from_pointer(void *p, uint64_t tagmask) {
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dst_t ret;
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ret.pointer = p;
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ret.u64 &= DST_NANBOX_POINTERBITS;
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ret.u64 |= tagmask;
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return ret;
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}
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static inline dst_t dst_nanbox_from_double(double d) {
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dst_t ret;
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ret.real = d;
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/* Normalize NaNs to nil */
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if (d != d)
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ret.u64 = dst_nanbox_tag(DST_T_NIL) << 48;
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return ret;
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}
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static inline dst_t dst_nanbox_from_bits(uint64_t bits) {
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dst_t ret;
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ret.u64 = bits;
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return ret;
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}
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#define dst_nanbox_truthy(x) \
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(~(dst_nanbox_checktype((x), DST_NIL) || dst_nanbox_checktype((x), DST_FALSE)))
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#define dst_nanbox_from_payload(t, p) \
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dst_nanbox_from_bits((dst_nanbox_tag(t) << 48) | (p))
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#define dst_nanbox_wrap_(p, t) \
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dst_nanbox_from_pointer((p), (dst_nanbox_tag(t) << 48) | 0x7FF8000000000000lu)
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/* Wrap the simple types */
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#define dst_nanbox_wrap_nil() dst_nanbox_from_payload(DST_T_NIL, 0xFFFFFFFFFFFFlu)
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#define dst_nanbox_wrap_true() dst_nanbox_from_payload(DST_T_TRUE, 0xFFFFFFFFFFFFlu)
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#define dst_nanbox_wrap_false() dst_nanbox_from_payload(DST_T_FALSE, 0xFFFFFFFFFFFFlu)
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#define dst_nanbox_wrap_boolean(b) dst_nanbox_from_payload((b) ? DST_T_TRUE : DST_T_FALSE, 0xFFFFFFFFFFFFlu)
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#define dst_nanbox_wrap_integer(i) dst_nanbox_from_payload(DST_T_INTEGER, (uint32_t)(i))
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#define dst_nanbox_wrap_real(r) dst_nanbox_from_double(r)
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#define dst_nanbox_unwrap_boolean(x) \
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(((x).u64 >> 48) == dst_nanbox_tag(DST_T_TRUE))
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#define dst_nanbox_unwrap_integer(x) \
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((int32_t)((x).u64 & 0xFFFFFFFFlu))
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#define dst_nanbox_unwrap_real(x) ((x).real)
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/* Wrap the pointer types */
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#define dst_nanbox_wrap_struct(s) dst_nanbox_wrap_((s), DST_T_STRUCT)
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#define dst_nanbox_wrap_tuple(s) dst_nanbox_wrap_((s), DST_T_TUPLE)
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#define dst_nanbox_wrap_fiber(s) dst_nanbox_wrap_((s), DST_T_FIBER)
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#define dst_nanbox_wrap_array(s) dst_nanbox_wrap_((s), DST_T_ARRAY)
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#define dst_nanbox_wrap_table(s) dst_nanbox_wrap_((s), DST_T_TABLE)
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#define dst_nanbox_wrap_buffer(s) dst_nanbox_wrap_((s), DST_T_BUFFER)
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#define dst_nanbox_wrap_string(s) dst_nanbox_wrap_((s), DST_T_STRING)
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#define dst_nanbox_wrap_symbol(s) dst_nanbox_wrap_((s), DST_T_SYMBOL)
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#define dst_nanbox_wrap_userdata(s) dst_nanbox_wrap_((s), DST_T_USERDATA)
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#define dst_nanbox_wrap_function(s) dst_nanbox_wrap_((s), DST_T_FUNCTION)
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#define dst_nanbox_wrap_cfunction(s) dst_nanbox_wrap_((s), DST_T_CFUNCTION)
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/* Unwrap the pointer types */
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#define dst_nanbox_unwrap_struct(x) ((const DstValue *)dst_nanbox_to_pointer(x))
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#define dst_nanbox_unwrap_tuple(x) ((const DstValue *)dst_nanbox_to_pointer(x))
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#define dst_nanbox_unwrap_fiber(x) ((DstFiber *)dst_nanbox_to_pointer(x))
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#define dst_nanbox_unwrap_array(x) ((DstArray *)dst_nanbox_to_pointer(x))
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#define dst_nanbox_unwrap_table(x) ((DstTable *)dst_nanbox_to_pointer(x))
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#define dst_nanbox_unwrap_buffer(x) ((DstBuffer *)dst_nanbox_to_pointer(x))
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#define dst_nanbox_unwrap_string(x) ((const uint8_t *)dst_nanbox_to_pointer(x))
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#define dst_nanbox_unwrap_symbol(x) ((const uint8_t *)dst_nanbox_to_pointer(x))
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#define dst_nanbox_unwrap_userdata(x) (dst_nanbox_to_pointer(x))
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#define dst_nanbox_unwrap_function(x) ((DstFunction *)dst_nanbox_to_pointer(x))
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#define dst_nanbox_unwrap_cfunction(x) ((DstCFunction)dst_nanbox_to_pointer(x))
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void dst_nanbox_print(dst_t x) {
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assert(dst_nanbox_checktype(x, dst_nanbox_type(x)));
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printf("hex: 0x%llx, "
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"description: ", x.u64);
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switch (dst_nanbox_type(x)) {
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case DST_T_NIL:
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printf("nil\n");
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break;
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case DST_T_TRUE:
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printf("true\n");
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break;
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case DST_T_FALSE:
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printf("false\n");
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break;
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case DST_T_INTEGER:
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printf("%dI\n", dst_nanbox_unwrap_integer(x));
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break;
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case DST_T_STRUCT:
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printf("<struct %p>\n", dst_nanbox_unwrap_struct(x));
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break;
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case DST_T_TUPLE:
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printf("<tuple %p>\n", dst_nanbox_unwrap_tuple(x));
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break;
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case DST_T_FIBER:
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printf("<fiber %p>\n", dst_nanbox_unwrap_fiber(x));
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break;
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case DST_T_ARRAY:
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printf("<array %p>\n", dst_nanbox_unwrap_array(x));
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break;
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case DST_T_TABLE:
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printf("<table %p>\n", dst_nanbox_unwrap_table(x));
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break;
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case DST_T_STRING:
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printf("<string %p>\n", dst_nanbox_unwrap_string(x));
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break;
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case DST_T_SYMBOL:
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printf("<symbol %p>\n", dst_nanbox_unwrap_symbol(x));
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break;
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case DST_T_USERDATA:
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printf("<userdata %p>\n", dst_nanbox_unwrap_userdata(x));
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break;
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case DST_T_FUNCTION:
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printf("<function %p>\n", dst_nanbox_unwrap_function(x));
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break;
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case DST_T_CFUNCTION:
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printf("<cfunction %p>\n", dst_nanbox_unwrap_cfunction(x));
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break;
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case DST_T_BUFFER:
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printf("<buffer %p>\n", dst_nanbox_unwrap_buffer(x));
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break;
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default:
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printf("unknown type 0x%llu\n", dst_nanbox_type(x));
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case DST_T_REAL:
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printf("%.21g\n", dst_nanbox_unwrap_real(x));
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break;
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}
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}
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int main() {
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printf("--- nan box test ---\n");
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printf("sizeof(dst_t) = %lu\n", sizeof(dst_t));
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DstArray array;
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dst_nanbox_print(dst_nanbox_wrap_real(0.125));
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dst_nanbox_print(dst_nanbox_wrap_real(19236910.125));
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dst_nanbox_print(dst_nanbox_wrap_real(123120.125));
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dst_nanbox_print(dst_nanbox_wrap_real(0.0));
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dst_nanbox_print(dst_nanbox_wrap_real(1.0/0.0));
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dst_nanbox_print(dst_nanbox_wrap_real(1.0/-0.0));
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dst_nanbox_print(dst_nanbox_wrap_real(0.0/-0.0));
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dst_nanbox_print(dst_nanbox_wrap_real(0.0/0.0));
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dst_nanbox_print(dst_nanbox_wrap_true());
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dst_nanbox_print(dst_nanbox_wrap_false());
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dst_nanbox_print(dst_nanbox_wrap_integer(123));
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dst_nanbox_print(dst_nanbox_wrap_integer(-123));
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dst_nanbox_print(dst_nanbox_wrap_integer(0));
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dst_nanbox_print(dst_nanbox_wrap_array(&array));
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dst_nanbox_print(dst_nanbox_wrap_table(&array));
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dst_nanbox_print(dst_nanbox_wrap_string(&array));
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dst_nanbox_print(dst_nanbox_wrap_buffer(&array));
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printf("--- nan box test end ---\n");
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}
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