sw/device/tests/kelvin/kelvin_checksum.c

/*
 * Copyright 2023 Google LLC
 *
 * 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.
 */

// A kelvin program that computes the checksum from a range of the memory.

#include <stddef.h>
#include <stdint.h>

const uint32_t kInput = 0x300000;
const uint32_t kOutput = 0x380000;
const int kImageWords = 320 * 240 / sizeof(uint32_t);

int main(int argc, char *argv[]) {
  const uint32_t *input = (const uint32_t *)kInput;
  uint32_t *output = (uint32_t *)kOutput;

  uint32_t checksum = 0;

  for (int i = 0; i < kImageWords; ++i) {
    checksum += input[i];
  }

  *output = checksum;

  // Flush the output value to the address 0x380000.
  asm volatile("lw a5, %0" : : "m"(output));
  asm volatile(".word 0x26078077");  // flushat a5
  return 0;
}