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fields.cpp
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fields.cpp
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/* Copyright 2013-present Barefoot Networks, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Antonin Bas ([email protected])
*
*/
#include <bm/bm_sim/fields.h>
#include <bm/bm_sim/headers.h>
#include <algorithm> // for std::swap
#include "extract.h"
namespace bm {
Field::Field(int nbits, Header *parent_hdr, bool arith_flag, bool is_signed,
bool hidden, bool VL, bool is_saturating)
: nbits(nbits), nbytes((nbits + 7) / 8), bytes(nbytes),
parent_hdr(parent_hdr),
is_signed(is_signed), hidden(hidden), VL(VL),
is_saturating(is_saturating) {
arith = arith_flag;
// TODO(antonin) ?
// should I only do that for arith fields ?
mask <<= nbits; mask -= 1;
if (is_signed) {
assert(nbits > 1);
max <<= (nbits - 1); max -= 1;
min <<= (nbits - 1); min *= -1;
} else {
max = mask;
min = 0;
}
}
void
Field::reserve_VL(size_t max_bytes) {
if (VL) bytes.reserve(max_bytes);
}
void
Field::swap_values(Field *other) {
// do not swap arith!
std::swap(value, other->value);
std::swap(bytes, other->bytes);
if (VL) {
std::swap(nbits, other->nbits);
std::swap(nbytes, other->nbytes);
std::swap(mask, other->mask);
assert(is_signed == other->is_signed);
assert(is_saturating == other->is_saturating);
std::swap(max, other->max);
std::swap(min, other->min);
}
}
int
Field::extract(const char *data, int hdr_offset) {
extract::generic_extract(data, hdr_offset, nbits, bytes.data());
if (arith) sync_value();
return nbits;
}
int
Field::extract_VL(const char *data, int hdr_offset, int computed_nbits) {
nbits = computed_nbits;
nbytes = (nbits + 7) / 8;
mask = 1; mask <<= nbits; mask -= 1;
bytes.resize(nbytes);
if (is_signed) {
assert(nbits > 1);
max <<= (nbits - 1); max -= 1;
min <<= (nbits - 1); min *= -1;
} else {
max = mask;
min = 0;
}
return Field::extract(data, hdr_offset);
}
int
Field::deparse(char *data, int hdr_offset) const {
// this does not work for empty variable-length fields, as we assert in the
// ByteContainer's [] operator. The right thing to do would probably be to add
// a at() method to ByteContainer and not perform any check in [].
// extract::generic_deparse(&bytes[0], nbits, data, hdr_offset);
extract::generic_deparse(bytes.data(), nbits, data, hdr_offset);
return nbits;
}
void
Field::assign_VL(const Field &src) {
assert(VL);
nbits = src.nbits;
nbytes = src.nbytes;
bytes.resize(nbytes);
mask = src.mask;
max = src.max;
min = src.min;
set(src);
parent_hdr->recompute_nbytes_packet();
}
void
Field::reset_VL() {
assert(VL);
nbits = 0;
nbytes = 0;
mask = 1;
if (is_signed) {
max = 1;
min = 1;
}
}
void
Field::copy_value(const Field &src) {
// it's important to have a way of copying a field value without the
// packet_id pointer. This is used by PHV::copy_headers().
value = src.value;
bytes = src.bytes;
if (VL) {
nbits = src.nbits;
nbytes = src.nbytes;
mask = src.mask;
min = src.min;
max = src.max;
}
}
} // namespace bm