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Annotation of qemu/roms/sgabios/csum8.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright 2010 Google Inc.
        !             3:  *
        !             4:  * Licensed under the Apache License, Version 2.0 (the "License");
        !             5:  * you may not use this file except in compliance with the License.
        !             6:  * You may obtain a copy of the License at
        !             7:  *
        !             8:  *     http://www.apache.org/licenses/LICENSE-2.0
        !             9:  *
        !            10:  * Unless required by applicable law or agreed to in writing, software
        !            11:  * distributed under the License is distributed on an "AS IS" BASIS,
        !            12:  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
        !            13:  * See the License for the specific language governing permissions and
        !            14:  * limitations under the License.
        !            15:  *
        !            16:  * compute rom checksum byte
        !            17:  */
        !            18: 
        !            19: #include <stdio.h>
        !            20: #include <unistd.h>
        !            21: #include <stdlib.h>
        !            22: #include <fcntl.h>
        !            23: #include <sys/types.h>
        !            24: 
        !            25: #define MAX_SIZE 65536
        !            26: unsigned char buf[MAX_SIZE];
        !            27: 
        !            28: int main(int argc, char **argv)
        !            29: {
        !            30:   ssize_t fsize;
        !            31:   int i, sum, fd;
        !            32:   unsigned char csum;
        !            33: 
        !            34:   if (argc < 2) {
        !            35:     fprintf(stderr, "usage: %s filename\n", argv[0]);
        !            36:     exit(1);
        !            37:   }
        !            38:   if ((fd = open(argv[1], O_RDWR)) < 0) {
        !            39:     perror(argv[1]);
        !            40:     exit(1);
        !            41:   }
        !            42:   if ((fsize = read(fd, buf, MAX_SIZE)) < 0) {
        !            43:     perror(argv[1]);
        !            44:     exit(1);
        !            45:   }
        !            46:   if (fsize >= MAX_SIZE && read(fd, &buf[MAX_SIZE - 1], 1) > 0) {
        !            47:     fprintf(stderr, "FAIL: %s is larger than %d bytes\n", argv[1], MAX_SIZE);
        !            48:     exit(1);
        !            49:   }
        !            50:   i = fsize - 2048 * (fsize / 2048);
        !            51:   if (i != 2047) {
        !            52:     fprintf(stderr, "FAIL: %s is %zd bytes, need 2K pad-1\n", argv[1], fsize);
        !            53:     exit(1);
        !            54:   }
        !            55:   for (i = sum = 0; i < fsize; i++) {
        !            56:     sum += buf[i];
        !            57:   }
        !            58:   sum &= 0xff;
        !            59:   csum = -sum & 0xff;
        !            60:   write(fd, &csum, 1);
        !            61:   close(fd);
        !            62:   fprintf(stderr, "%s: sum = 0x%02x, wrote byte 0x%02x\n", argv[1], sum, csum);
        !            63:   return 0;
        !            64: }

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