Age of Empires (1997) 與 Age of Empires II: The Age of Kings (1999) 是當年兩個很紅的遊戲，有傳言裡面有很大一部分是用組合語言寫的。

剛剛在 Hacker News 上看到「Original Age of Empires 2 dev talks about its usage of assembly code (reddit.com)」這篇，看起來是原作者跳出來說明這段傳言 (講的更細)，原文在 Reddit 的「AoE is written in Assembly - is this actually TRUE?! :O : aoe2」這邊。

32-bit 的 x86 組語部分有大約 13k 行，大多數 (11.5k 行) 是與繪圖有關的 (當年繪圖相關的功能都還是 CPU 在算)：

There were about ~13,000 lines of x86 32-bit assembly code written in total.

The vast majority, about ~11,500 lines worth, was in the 'drawing core', which drew SLP sprites in a variety of ways (mirrored, stippled, clipped). The code for this was in a separate .asm file, which was "compiled" by Microsoft Macro Assembler 6.1 into a .obj file.

最主要的目的當然是效能，這邊提到隔壁棚的星海爭霸預設還是 640x480 的時候，AoE 這邊預設可以上 800x600：

The use of assembly in the drawing core resulting in a ~10x sprite drawing speed improvement over the C++ reference implementations, and AoE's drawing core was notably faster than competitors like StarCraft, which is why the default resolution 'out of the box' for AoE was 800 by 600, when nearly all our competition was 640 x 480 resolution - we could scroll the screen and fill it with sprites as fast or faster even though we had twice as many pixels-ish in the game world area.

後來到 64-bit 年代就變成用 C++，主要是因為 compiler optimization 的改進，以及多 CPU 與 multi-threading 的技術，讓計算力提升很多：

I re-wrote the assembly functions into C++ for both Definitive Editions, as they are 64-bit programs, and inline assembly was never supported by the 64-bit C++ compiler, and the vastly improved register sets and compiler optimizations made it un-necessary. Additionally, sprite drawing in the definitive editions is multi-threaded, and will use up to 4 cores for that task alone.

算是時代的演進，意外的留下一些記錄... 而更後面的時代則是把這些計算 offload 到顯卡上面了。

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