1 files changed, 64 insertions, 0 deletions
diff --git a/src/roms/sgabios/csum8.c b/src/roms/sgabios/csum8.c
new file mode 100644
index 0000000..6962913
--- /dev/null
+++ b/src/roms/sgabios/csum8.c
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2010 Google 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.
+ *
+ * compute rom checksum byte
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/types.h>
+
+#define MAX_SIZE 65536
+unsigned char buf[MAX_SIZE];
+
+int main(int argc, char **argv)
+{
+  ssize_t fsize;
+  int i, sum, fd;
+  unsigned char csum;
+
+  if (argc < 2) {
+    fprintf(stderr, "usage: %s filename\n", argv[0]);
+    exit(1);
+  }
+  if ((fd = open(argv[1], O_RDWR)) < 0) {
+    perror(argv[1]);
+    exit(1);
+  }
+  if ((fsize = read(fd, buf, MAX_SIZE)) < 0) {
+    perror(argv[1]);
+    exit(1);
+  }
+  if (fsize >= MAX_SIZE && read(fd, &buf[MAX_SIZE - 1], 1) > 0) {
+    fprintf(stderr, "FAIL: %s is larger than %d bytes\n", argv[1], MAX_SIZE);
+    exit(1);
+  }
+  i = fsize - 2048 * (fsize / 2048);
+  if (i != 2047) {
+    fprintf(stderr, "FAIL: %s is %zd bytes, need 2K pad-1\n", argv[1], fsize);
+    exit(1);
+  }
+  for (i = sum = 0; i < fsize; i++) {
+    sum += buf[i];
+  }
+  sum &= 0xff;
+  csum = -sum & 0xff;
+  write(fd, &csum, 1);
+  close(fd);
+  fprintf(stderr, "%s: sum = 0x%02x, wrote byte 0x%02x\n", argv[1], sum, csum);
+  return 0;
+}