背景

CやC++でFPGAやハードウェアを制御する場合、まずは自分の環境でデータの型を確認した方が良い。そういう場合のちょっとしたコードです。

サンプルコード

どこでもよいので、下記を挿入する。

  double *dbl_pnt;
  int    *int_pnt;
  long    *long_pnt;
  long long  *longlong_pnt;
  printf("> Basic data type:\n");
  printf("  sizeof (char)     = %d\n", sizeof(char));
  printf("  sizeof (uchar)    = %d\n", sizeof(unsigned char));
  printf("  sizeof (short)    = %d\n", sizeof(short));
  printf("  sizeof (ushort)   = %d\n", sizeof(unsigned short));
  printf("  sizeof (int)      = %d\n", sizeof(int));
  printf("  sizeof (*int)     = %d\n", sizeof(int_pnt));
  printf("  sizeof (float)    = %d\n", sizeof(float));
  printf("  sizeof (double)   = %d\n", sizeof(double));
  printf("  sizeof (*double)  = %d\n", sizeof(dbl_pnt));

  printf("  sizeof (long)      = %d\n", sizeof(long));
  printf("  sizeof (*long)     = %d\n", sizeof(long_pnt));

  printf("  sizeof (long long )      = %d\n", sizeof(long long ));
  printf("  sizeof (*long long )     = %d\n", sizeof(longlong_pnt));

出力結果は、

> Basic data type:
  sizeof (char)     = 1
  sizeof (uchar)    = 1
  sizeof (short)    = 2
  sizeof (ushort)   = 2
  sizeof (int)      = 4
  sizeof (*int)     = 8
  sizeof (float)    = 4
  sizeof (double)   = 8
  sizeof (*double)  = 8
  sizeof (long)      = 8
  sizeof (*long)     = 8
  sizeof (long long )      = 8
  sizeof (*long long )     = 8

上記の結果は、下記の環境で取得された。

> gcc -v                                  
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 7.3.0 (clang-703.0.31)
Target: x86_64-apple-darwin15.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

参考資料

３次元磁気流体シミュレーションコード pluto の main.c