526 lines
13 KiB
C
526 lines
13 KiB
C
/* go-reflect-call.c -- call reflection support for Go.
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Copyright 2009 The Go Authors. All rights reserved.
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Use of this source code is governed by a BSD-style
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license that can be found in the LICENSE file. */
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#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include "runtime.h"
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#include "go-alloc.h"
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#include "go-assert.h"
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#include "go-type.h"
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#ifdef USE_LIBFFI
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#include "ffi.h"
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/* The functions in this file are only called from reflect_call. As
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reflect_call calls a libffi function, which will be compiled
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without -fsplit-stack, it will always run with a large stack. */
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static ffi_type *go_array_to_ffi (const struct __go_array_type *)
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__attribute__ ((no_split_stack));
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static ffi_type *go_slice_to_ffi (const struct __go_slice_type *)
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__attribute__ ((no_split_stack));
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static ffi_type *go_struct_to_ffi (const struct __go_struct_type *)
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__attribute__ ((no_split_stack));
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static ffi_type *go_string_to_ffi (void) __attribute__ ((no_split_stack));
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static ffi_type *go_interface_to_ffi (void) __attribute__ ((no_split_stack));
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static ffi_type *go_complex_to_ffi (ffi_type *)
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__attribute__ ((no_split_stack));
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static ffi_type *go_type_to_ffi (const struct __go_type_descriptor *)
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__attribute__ ((no_split_stack));
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static ffi_type *go_func_return_ffi (const struct __go_func_type *)
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__attribute__ ((no_split_stack));
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static void go_func_to_cif (const struct __go_func_type *, _Bool, _Bool,
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ffi_cif *)
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__attribute__ ((no_split_stack));
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static size_t go_results_size (const struct __go_func_type *)
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__attribute__ ((no_split_stack));
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static void go_set_results (const struct __go_func_type *, unsigned char *,
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void **)
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__attribute__ ((no_split_stack));
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/* Return an ffi_type for a Go array type. The libffi library does
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not have any builtin support for passing arrays as values. We work
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around this by pretending that the array is a struct. */
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static ffi_type *
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go_array_to_ffi (const struct __go_array_type *descriptor)
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{
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ffi_type *ret;
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uintptr_t len;
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ffi_type *element;
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uintptr_t i;
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ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
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ret->type = FFI_TYPE_STRUCT;
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len = descriptor->__len;
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ret->elements = (ffi_type **) __go_alloc ((len + 1) * sizeof (ffi_type *));
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element = go_type_to_ffi (descriptor->__element_type);
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for (i = 0; i < len; ++i)
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ret->elements[i] = element;
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ret->elements[len] = NULL;
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return ret;
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}
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/* Return an ffi_type for a Go slice type. This describes the
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__go_open_array type defines in array.h. */
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static ffi_type *
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go_slice_to_ffi (
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const struct __go_slice_type *descriptor __attribute__ ((unused)))
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{
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ffi_type *ret;
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ffi_type *ffi_intgo;
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ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
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ret->type = FFI_TYPE_STRUCT;
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ret->elements = (ffi_type **) __go_alloc (4 * sizeof (ffi_type *));
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ret->elements[0] = &ffi_type_pointer;
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ffi_intgo = sizeof (intgo) == 4 ? &ffi_type_sint32 : &ffi_type_sint64;
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ret->elements[1] = ffi_intgo;
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ret->elements[2] = ffi_intgo;
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ret->elements[3] = NULL;
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return ret;
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}
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/* Return an ffi_type for a Go struct type. */
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static ffi_type *
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go_struct_to_ffi (const struct __go_struct_type *descriptor)
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{
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ffi_type *ret;
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int field_count;
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const struct __go_struct_field *fields;
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int i;
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ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
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ret->type = FFI_TYPE_STRUCT;
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field_count = descriptor->__fields.__count;
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fields = (const struct __go_struct_field *) descriptor->__fields.__values;
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ret->elements = (ffi_type **) __go_alloc ((field_count + 1)
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* sizeof (ffi_type *));
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for (i = 0; i < field_count; ++i)
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ret->elements[i] = go_type_to_ffi (fields[i].__type);
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ret->elements[field_count] = NULL;
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return ret;
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}
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/* Return an ffi_type for a Go string type. This describes the String
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struct. */
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static ffi_type *
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go_string_to_ffi (void)
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{
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ffi_type *ret;
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ffi_type *ffi_intgo;
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ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
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ret->type = FFI_TYPE_STRUCT;
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ret->elements = (ffi_type **) __go_alloc (3 * sizeof (ffi_type *));
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ret->elements[0] = &ffi_type_pointer;
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ffi_intgo = sizeof (intgo) == 4 ? &ffi_type_sint32 : &ffi_type_sint64;
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ret->elements[1] = ffi_intgo;
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ret->elements[2] = NULL;
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return ret;
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}
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/* Return an ffi_type for a Go interface type. This describes the
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__go_interface and __go_empty_interface structs. */
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static ffi_type *
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go_interface_to_ffi (void)
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{
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ffi_type *ret;
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ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
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ret->type = FFI_TYPE_STRUCT;
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ret->elements = (ffi_type **) __go_alloc (3 * sizeof (ffi_type *));
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ret->elements[0] = &ffi_type_pointer;
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ret->elements[1] = &ffi_type_pointer;
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ret->elements[2] = NULL;
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return ret;
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}
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/* Return an ffi_type for a Go complex type. */
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static ffi_type *
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go_complex_to_ffi (ffi_type *float_type)
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{
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ffi_type *ret;
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ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
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ret->type = FFI_TYPE_STRUCT;
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ret->elements = (ffi_type **) __go_alloc (3 * sizeof (ffi_type *));
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ret->elements[0] = float_type;
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ret->elements[1] = float_type;
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ret->elements[2] = NULL;
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return ret;
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}
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/* Return an ffi_type for a type described by a
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__go_type_descriptor. */
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static ffi_type *
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go_type_to_ffi (const struct __go_type_descriptor *descriptor)
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{
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switch (descriptor->__code & GO_CODE_MASK)
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{
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case GO_BOOL:
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if (sizeof (_Bool) == 1)
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return &ffi_type_uint8;
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else if (sizeof (_Bool) == sizeof (int))
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return &ffi_type_uint;
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abort ();
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case GO_FLOAT32:
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if (sizeof (float) == 4)
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return &ffi_type_float;
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abort ();
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case GO_FLOAT64:
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if (sizeof (double) == 8)
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return &ffi_type_double;
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abort ();
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case GO_COMPLEX64:
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if (sizeof (float) == 4)
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return go_complex_to_ffi (&ffi_type_float);
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abort ();
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case GO_COMPLEX128:
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if (sizeof (double) == 8)
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return go_complex_to_ffi (&ffi_type_double);
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abort ();
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case GO_INT16:
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return &ffi_type_sint16;
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case GO_INT32:
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return &ffi_type_sint32;
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case GO_INT64:
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return &ffi_type_sint64;
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case GO_INT8:
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return &ffi_type_sint8;
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case GO_INT:
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return sizeof (intgo) == 4 ? &ffi_type_sint32 : &ffi_type_sint64;
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case GO_UINT16:
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return &ffi_type_uint16;
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case GO_UINT32:
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return &ffi_type_uint32;
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case GO_UINT64:
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return &ffi_type_uint64;
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case GO_UINT8:
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return &ffi_type_uint8;
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case GO_UINT:
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return sizeof (uintgo) == 4 ? &ffi_type_uint32 : &ffi_type_uint64;
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case GO_UINTPTR:
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if (sizeof (void *) == 2)
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return &ffi_type_uint16;
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else if (sizeof (void *) == 4)
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return &ffi_type_uint32;
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else if (sizeof (void *) == 8)
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return &ffi_type_uint64;
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abort ();
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case GO_ARRAY:
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return go_array_to_ffi ((const struct __go_array_type *) descriptor);
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case GO_SLICE:
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return go_slice_to_ffi ((const struct __go_slice_type *) descriptor);
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case GO_STRUCT:
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return go_struct_to_ffi ((const struct __go_struct_type *) descriptor);
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case GO_STRING:
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return go_string_to_ffi ();
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case GO_INTERFACE:
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return go_interface_to_ffi ();
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case GO_CHAN:
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case GO_FUNC:
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case GO_MAP:
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case GO_PTR:
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case GO_UNSAFE_POINTER:
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/* These types are always pointers, and for FFI purposes nothing
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else matters. */
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return &ffi_type_pointer;
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default:
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abort ();
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}
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}
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/* Return the return type for a function, given the number of out
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parameters and their types. */
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static ffi_type *
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go_func_return_ffi (const struct __go_func_type *func)
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{
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int count;
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const struct __go_type_descriptor **types;
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ffi_type *ret;
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int i;
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count = func->__out.__count;
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if (count == 0)
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return &ffi_type_void;
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types = (const struct __go_type_descriptor **) func->__out.__values;
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if (count == 1)
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return go_type_to_ffi (types[0]);
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ret = (ffi_type *) __go_alloc (sizeof (ffi_type));
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ret->type = FFI_TYPE_STRUCT;
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ret->elements = (ffi_type **) __go_alloc ((count + 1) * sizeof (ffi_type *));
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for (i = 0; i < count; ++i)
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ret->elements[i] = go_type_to_ffi (types[i]);
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ret->elements[count] = NULL;
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return ret;
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}
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/* Build an ffi_cif structure for a function described by a
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__go_func_type structure. */
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static void
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go_func_to_cif (const struct __go_func_type *func, _Bool is_interface,
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_Bool is_method, ffi_cif *cif)
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{
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int num_params;
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const struct __go_type_descriptor **in_types;
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size_t num_args;
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ffi_type **args;
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int off;
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int i;
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ffi_type *rettype;
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ffi_status status;
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num_params = func->__in.__count;
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in_types = ((const struct __go_type_descriptor **)
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func->__in.__values);
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num_args = num_params + (is_interface ? 1 : 0);
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args = (ffi_type **) __go_alloc (num_args * sizeof (ffi_type *));
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i = 0;
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off = 0;
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if (is_interface)
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{
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args[0] = &ffi_type_pointer;
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off = 1;
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}
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else if (is_method)
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{
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args[0] = &ffi_type_pointer;
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i = 1;
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}
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for (; i < num_params; ++i)
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args[i + off] = go_type_to_ffi (in_types[i]);
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rettype = go_func_return_ffi (func);
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status = ffi_prep_cif (cif, FFI_DEFAULT_ABI, num_args, rettype, args);
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__go_assert (status == FFI_OK);
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}
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/* Get the total size required for the result parameters of a
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function. */
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static size_t
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go_results_size (const struct __go_func_type *func)
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{
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int count;
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const struct __go_type_descriptor **types;
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size_t off;
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size_t maxalign;
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int i;
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count = func->__out.__count;
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if (count == 0)
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return 0;
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types = (const struct __go_type_descriptor **) func->__out.__values;
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/* A single integer return value is always promoted to a full
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word. */
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if (count == 1)
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{
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switch (types[0]->__code & GO_CODE_MASK)
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{
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case GO_BOOL:
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case GO_INT8:
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case GO_INT16:
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case GO_INT32:
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case GO_UINT8:
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case GO_UINT16:
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case GO_UINT32:
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case GO_INT:
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case GO_UINT:
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return sizeof (ffi_arg);
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default:
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break;
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}
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}
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off = 0;
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maxalign = 0;
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for (i = 0; i < count; ++i)
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{
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size_t align;
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align = types[i]->__field_align;
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if (align > maxalign)
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maxalign = align;
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off = (off + align - 1) & ~ (align - 1);
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off += types[i]->__size;
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}
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off = (off + maxalign - 1) & ~ (maxalign - 1);
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return off;
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}
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/* Copy the results of calling a function via FFI from CALL_RESULT
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into the addresses in RESULTS. */
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static void
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go_set_results (const struct __go_func_type *func, unsigned char *call_result,
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void **results)
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{
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int count;
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const struct __go_type_descriptor **types;
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size_t off;
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int i;
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count = func->__out.__count;
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if (count == 0)
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return;
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types = (const struct __go_type_descriptor **) func->__out.__values;
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/* A single integer return value is always promoted to a full
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word. */
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if (count == 1)
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{
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switch (types[0]->__code & GO_CODE_MASK)
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{
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case GO_BOOL:
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case GO_INT8:
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case GO_INT16:
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case GO_INT32:
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case GO_UINT8:
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case GO_UINT16:
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case GO_UINT32:
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case GO_INT:
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case GO_UINT:
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{
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union
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{
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unsigned char buf[sizeof (ffi_arg)];
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ffi_arg v;
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} u;
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ffi_arg v;
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__builtin_memcpy (&u.buf, call_result, sizeof (ffi_arg));
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v = u.v;
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switch (types[0]->__size)
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{
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case 1:
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{
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uint8_t b;
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b = (uint8_t) v;
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__builtin_memcpy (results[0], &b, 1);
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}
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break;
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case 2:
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{
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uint16_t s;
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s = (uint16_t) v;
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__builtin_memcpy (results[0], &s, 2);
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}
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break;
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case 4:
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{
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uint32_t w;
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w = (uint32_t) v;
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__builtin_memcpy (results[0], &w, 4);
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}
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break;
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case 8:
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{
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uint64_t d;
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d = (uint64_t) v;
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__builtin_memcpy (results[0], &d, 8);
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}
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break;
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default:
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abort ();
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}
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}
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return;
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default:
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break;
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}
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}
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off = 0;
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for (i = 0; i < count; ++i)
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{
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size_t align;
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size_t size;
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align = types[i]->__field_align;
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size = types[i]->__size;
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off = (off + align - 1) & ~ (align - 1);
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__builtin_memcpy (results[i], call_result + off, size);
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off += size;
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}
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}
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/* Call a function. The type of the function is FUNC_TYPE, and the
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address is FUNC_ADDR. PARAMS is an array of parameter addresses.
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RESULTS is an array of result addresses. */
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void
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reflect_call (const struct __go_func_type *func_type, const void *func_addr,
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_Bool is_interface, _Bool is_method, void **params,
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void **results)
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{
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ffi_cif cif;
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unsigned char *call_result;
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__go_assert ((func_type->__common.__code & GO_CODE_MASK) == GO_FUNC);
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go_func_to_cif (func_type, is_interface, is_method, &cif);
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call_result = (unsigned char *) malloc (go_results_size (func_type));
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ffi_call (&cif, func_addr, call_result, params);
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/* Some day we may need to free result values if RESULTS is
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NULL. */
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if (results != NULL)
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go_set_results (func_type, call_result, results);
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free (call_result);
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}
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#else /* !defined(USE_LIBFFI) */
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void
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reflect_call (const struct __go_func_type *func_type __attribute__ ((unused)),
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const void *func_addr __attribute__ ((unused)),
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_Bool is_interface __attribute__ ((unused)),
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_Bool is_method __attribute__ ((unused)),
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void **params __attribute__ ((unused)),
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void **results __attribute__ ((unused)))
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{
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/* Without FFI there is nothing we can do. */
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runtime_throw("libgo built without FFI does not support "
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"reflect.Call or runtime.SetFinalizer");
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}
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#endif /* !defined(USE_LIBFFI) */
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