mem.cc

/*
 * Copyright 2021 Max Planck Institute for Software Systems, and
 * National University of Singapore
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include "sims/nic/corundum/mem.h"

#include <iostream>

#include "sims/nic/corundum/debug.h"
#include "sims/nic/corundum/dma.h"

/*
 * 1024 bits total data width
 * = 128 bytes total
 *
 * 1024 / 8 = 128 bit per segment
 * = 16 bytes / segment
 */

#define DATA_WIDTH (512 * 2)
#define SEG_COUNT 8
#define SEG_WIDTH (DATA_WIDTH / SEG_COUNT)

void MemWriter::step() {
  if (cur && p.mem_ready && ((p.mem_ready & p.mem_valid) == p.mem_valid)) {
#ifdef MEM_DEBUG
    std::cerr << "completed write to: " << cur->ram_addr << std::endl;
#endif
    p.mem_valid = 0;
    p.mem_be[0] = p.mem_be[1] = p.mem_be[2] = p.mem_be[3] = 0;

    if (cur_off == cur->len) {
      /* operation is done */
      pending.pop_front();
      cur->engine->mem_op_complete(cur);
      cur_off = 0;
    } else {
      /* operation is not done yet, we'll pick it back up */
    }
    cur = 0;
  } else if (!cur && !pending.empty()) {
    cur = pending.front();

#ifdef MEM_DEBUG
    std::cerr << "issuing write to " << cur->ram_addr << std::endl;
#endif

    size_t data_byte_width = DATA_WIDTH / 8;
    size_t data_offset = (cur->ram_addr + cur_off) % data_byte_width;

    /* first reset everything */
    p.mem_sel = 0;
    p.mem_addr[0] = p.mem_addr[1] = p.mem_addr[2] = 0;
    p.mem_be[0] = p.mem_be[1] = p.mem_be[2] = p.mem_be[3] = 0;
    p.mem_valid = 0;
    for (size_t i = 0; i < data_byte_width / 4; i++) p.mem_data[i] = 0;

    /* put data bytes in the right places */
    size_t off = data_offset;
    size_t cur_len = (cur->len - cur_off > data_byte_width - data_offset
                          ? data_byte_width - data_offset
                          : cur->len - cur_off);
    for (size_t i = 0; i < cur_len; i++, off++) {
      size_t byte_off = off % 4;
      p.mem_data[off / 4] |=
          (((uint32_t)cur->data[cur_off + i]) << (byte_off * 8));
      p.mem_be[off / 32] |= (1 << (off % 32));
      p.mem_valid |= (1 << (off / (SEG_WIDTH / 8)));
    }

    uint64_t seg_addr = (cur->ram_addr + cur_off) / data_byte_width;
    size_t seg_addr_bits = 12;

    // iterate over the address bit by bit
    for (size_t i = 0; i < seg_addr_bits; i++) {
      uint32_t bit = ((seg_addr >> i) & 0x1);
      // iterate over the segments
      for (size_t j = 0; j < SEG_COUNT; j++) {
        size_t dst_bit = j * seg_addr_bits + i;
        p.mem_addr[dst_bit / 32] |= (bit << (dst_bit % 32));
      }
    }

    cur_off += cur_len;
  }
}

void MemWriter::op_issue(DMAOp *op) {
#ifdef MEM_DEBUG
  std::cerr << "enqueued write to " << op->ram_addr << std::endl;
#endif
  pending.push_back(op);
}

void MemReader::step() {
  size_t data_byte_width = DATA_WIDTH / 8;

  if (cur && p.mem_resvalid &&
      ((p.mem_resvalid & p.mem_valid) == p.mem_valid)) {
#ifdef MEM_DEBUG
    std::cerr << "completed read from: " << std::hex << cur->ram_addr
              << std::endl;
    std::cerr << "  reval = " << (unsigned)p.mem_resvalid << std::endl;
#endif
    p.mem_valid = 0;
#ifdef MEM_DEBUG
    for (size_t i = 0; i < 32; i++)
      std::cerr << "    val = " << p.mem_data[i] << std::endl;
#endif

    size_t off = (cur->ram_addr + cur_off) % data_byte_width;
    size_t cur_len =
        (cur->len - cur_off > data_byte_width - off ? data_byte_width - off
                                                    : cur->len - cur_off);
    for (size_t i = 0; i < cur_len; i++, off++) {
      size_t byte_off = (off % 4);
      cur->data[cur_off + i] = (p.mem_data[off / 4] >> (byte_off * 8)) & 0xff;
    }
    cur_off += cur_len;

    if (cur_off == cur->len) {
      /* operation is done */
      pending.pop_front();
      cur->engine->mem_op_complete(cur);
      cur_off = 0;
    } else {
      /* operation is not done yet, we'll pick it back up */
    }

    cur = 0;
  } else if (!cur && !pending.empty()) {
    cur = pending.front();
    size_t data_offset = (cur->ram_addr + cur_off) % data_byte_width;

#ifdef MEM_DEBUG
    std::cerr << "issuing op=" << cur << " read from " << std::hex
              << cur->ram_addr << std::endl;
    std::cerr << "    off=" << data_offset << std::endl;
#endif

    /* first reset everything */
    p.mem_sel = 0;
    p.mem_addr[0] = p.mem_addr[1] = p.mem_addr[2] = 0;
    p.mem_valid = 0x0;

    /* put data bytes in the right places */
    size_t off = data_offset;
    size_t cur_len = (cur->len - cur_off > data_byte_width - data_offset
                          ? data_byte_width - data_offset
                          : cur->len - cur_off);
    for (size_t i = 0; i < cur_len; i++, off++) {
      p.mem_valid |= (1 << (off / (SEG_WIDTH / 8)));
    }
    // p.mem_resready = p.mem_valid;
    p.mem_resready = 0xff;

    uint64_t seg_addr = (cur->ram_addr + cur_off) / data_byte_width;
    size_t seg_addr_bits = 12;

    // iterate over the address bit by bit
    for (size_t i = 0; i < seg_addr_bits; i++) {
      uint32_t bit = ((seg_addr >> i) & 0x1);
      // iterate over the segments
      for (size_t j = 0; j < SEG_COUNT; j++) {
        size_t dst_bit = j * seg_addr_bits + i;
        p.mem_addr[dst_bit / 32] |= (bit << (dst_bit % 32));
      }
    }

#ifdef MEM_DEBUG
    for (size_t i = 0; i < 3; i++)
      std::cerr << "    addr = " << p.mem_addr[i] << std::endl;
    std::cerr << "    mem_valid = " << (unsigned)p.mem_valid << std::endl;
#endif
  }
}

void MemReader::op_issue(DMAOp *op) {
#ifdef MEM_DEBUG
  std::cerr << "enqueued read from " << op->ram_addr << std::endl;
#endif
  pending.push_back(op);
}