13 Comments

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  Post Author

  diginova

  Posted March 21, 2025 at 8:18 am

  Also read how a compiler can be written in the same language – https://en.wikipedia.org/wiki/Bootstrapping_%28compilers%29

  https://stackoverflow.com/a/18247926/15566831

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  Post Author

  Joker_vD

  Posted March 24, 2025 at 9:23 am

  Funnily enough, it is emphatically not a single-pass compiler.

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  Post Author

  aap_

  Posted March 24, 2025 at 10:32 am

  Probably one of my favorite pieces of software of all times. Learned so much from this!

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  Post Author

  bluetomcat

  Posted March 24, 2025 at 10:43 am

  Interesting usage of "extern" and "auto". Quite different from contemporary C:

      tree() {
          extern symbol, block, csym[], ctyp, isn,
          peeksym, opdope[], build, error, cp[], cmst[],
          space, ospace, cval, ossiz, exit, errflush, cmsiz;
  
          auto op[], opst[20], pp[], prst[20], andflg, o, p, ps, os;
          ...
  

  Looks like "extern" is used to bring global symbols into function scope. Everything looks to be "int" by default. Some array declarations are specifying a size, others are not. Are the "sizeless" arrays meant to be used as pointers only?

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  Post Author

  tanelpoder

  Posted March 24, 2025 at 10:49 am

  The first publicly available version of Oracle Database (v2 released in 1979) was written in assembly for PDP-11. Then Oracle rewrote v3 in C (1983) for portability across platforms. The mainframes at the time didn't have C compilers, so instead of writing a mainframe-specific database product in a different language (COBOL?), they just wrote a C compiler for mainframes too.

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  Post Author

  dark-star

  Posted March 24, 2025 at 10:51 am

  My favorite function, which some might say even made it into Windows ;-)

      waste()  /* waste space */
      {
       waste(waste(waste),waste(waste),waste(waste));
       waste(waste(waste),waste(waste),waste(waste));
       waste(waste(waste),waste(waste),waste(waste));
       waste(waste(waste),waste(waste),waste(waste));
       waste(waste(waste),waste(waste),waste(waste));
       waste(waste(waste),waste(waste),waste(waste));
       waste(waste(waste),waste(waste),waste(waste));
       waste(waste(waste),waste(waste),waste(waste));
      }

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  Post Author

  ChrisMarshallNY

  Posted March 24, 2025 at 12:07 pm

  This is my favorite function :): https://github.com/mortdeus/legacy-cc/blob/936e12cfc756773cb…

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  Post Author

  FeistySkink

  Posted March 24, 2025 at 12:10 pm

  Missed opportunity not calling it LegaC.

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  Post Author

  smackay

  Posted March 24, 2025 at 12:29 pm

  1972 is the answer to the question on the lips of everybody too busy to look at the source files.

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  Post Author

  ModernMech

  Posted March 24, 2025 at 1:24 pm

  I thought the first C compiler was written in B.

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  Post Author

  90s_dev

  Posted March 24, 2025 at 1:41 pm

  The thing I always loved about C was its simplicity, but in practice it's actually very complex with tons of nuance. Are there any low level languages like C that actually are simple, through and through? I looked into Zig and it seems to approach that simplicity, but I have reservations that I can't quite put my finger on…

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  Post Author

  tempodox

  Posted March 24, 2025 at 1:57 pm

  Highly interesting!

    main(argc, argv)
    int argv[];
  

  This is a culture shock. Did the PDP-11 not distinguish between `char` and `int`?

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  Post Author

  ZhiqiangWang

  Posted March 24, 2025 at 2:32 pm

  Can't stop thinking about Ken Thompson Hack. This should be a clean one …

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