99 lines
3.7 KiB
C
99 lines
3.7 KiB
C
/*
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* Copyright © 2022 Imagination Technologies Ltd.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#include <assert.h>
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#include <inttypes.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include "rogue_util.h"
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#include "util/macros.h"
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/**
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* \file rogue_util.c
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*
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* \brief Contains compiler utility and helper functions.
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*/
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/**
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* \brief Splits and distributes value "source" across "dest_bytes" according to
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* the ranges specified (from MSB to LSB).
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*
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* \param[in] source The source value to be distributed.
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* \param[in] rangelist The rangelist describing how to distribute "source".
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* \param[in] dest_size The size of the destination in bytes.
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* \param[in] dest_bytes The destination byte array.
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* \return false if invalid inputs were provided, else true.
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*/
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bool rogue_distribute_value(uint64_t source,
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const struct rogue_rangelist *rangelist,
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size_t dest_size,
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uint8_t dest_bytes[dest_size])
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{
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size_t total_bits_left = 0U;
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/* Check that "value" is actually representable in "total_bits" bits. */
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total_bits_left = rogue_rangelist_bits(rangelist);
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assert(util_last_bit64(source) <= total_bits_left &&
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"Value cannot be represented.");
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/* Iterate over each range. */
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for (size_t u = 0U; u < rangelist->num_ranges; ++u) {
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struct rogue_bitrange *range = &rangelist->ranges[u];
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size_t dest_bit = range->start;
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size_t bits_left = range->num;
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size_t bytes_covered = rogue_bytes_spilled(range) + 1;
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size_t base_byte = rogue_byte_index(range, dest_size);
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/* Iterate over each byte covered by the current range. */
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for (size_t b = 0U; b < bytes_covered; ++b) {
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size_t max_bits = rogue_max_bits(dest_bit);
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size_t bits_to_place = MIN2(bits_left, max_bits);
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size_t dest_byte_bit = dest_bit % 8;
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size_t source_bit = total_bits_left - 1;
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/* Mask and shuffle the source value so that it'll fit into the
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* correct place in the destination byte:
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*/
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/* Extract bits. */
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uint64_t value_masked =
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(source & BITMASK64_N(source_bit, bits_to_place));
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/* Shift all the way right. */
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value_masked >>= (1 + source_bit - bits_to_place);
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/* Shift left to the correct position. */
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value_masked <<= (1 + dest_byte_bit - bits_to_place);
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/* Place value into byte. */
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dest_bytes[base_byte + b] |= (value_masked & 0xff);
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dest_bit -= max_bits;
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bits_left -= bits_to_place;
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total_bits_left -= bits_to_place;
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}
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}
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return true;
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}
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