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/*
* nanowasm, a tiny WebAssembly/Wasm interpreter
* Copyright (C) 2023-2024 Xavier Del Campo Romero
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/.
*/
#include <nw/log.h>
#include <nw/ops.h>
#include <nanowasm/nw.h>
#include <nw/interp.h>
#include <nw/types.h>
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <string.h>
static int branch(struct nw_interp *const i, const varuint32 relative_depth)
{
const struct nw_block *b = i->fp->last_block;
static const char exc[] = "relative depth and block count mismatch";
for (varuint32 d = 0; b && d < relative_depth; d++)
b = b->prev;
if (!b)
{
LOG("%s: %s\n", __func__, exc);
i->exception = exc;
return -1;
}
if (fseek(i->f, b->pc, SEEK_SET))
{
LOG("%s: fseek(3): %s\n", __func__, strerror(errno));
i->exception = "I/O error";
return -1;
}
return 0;
}
static bool cond(struct nw_interp *const i)
{
int32_t value;
if (interp_stack_pop(i, &value, sizeof value))
{
LOG("%s: interp_stack_pop failed\n", __func__);
return -1;
}
return value;
}
static int br_if(struct nw_interp *const i, const varuint32 relative_depth)
{
if (cond(i) && branch(i, relative_depth))
{
LOG("%s: branch failed\n", __func__);
return -1;
}
return 0;
}
static int op(struct nw_interp *const i, FILE *const f)
{
varuint32 relative_depth;
if (varuint32_read(f, &relative_depth))
{
LOG("%s: varuint32_read failed\n", __func__);
return 1;
}
else if (i && br_if(i, relative_depth))
{
LOG("%s: br_if failed\n", __func__);
return -1;
}
return 0;
}
int op_br_if(struct nw_interp *const i)
{
return op(i, i->f);
}
int check_br_if(FILE *const f)
{
return op(NULL, f);
}
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