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wswan:guide:optimization_v30mz

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wswan:guide:optimization_v30mz [2024/02/17 20:10] – asiewswan:guide:optimization_v30mz [2024/02/17 20:11] (current) – asie
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 While the V30MZ is an 80186-compatible CPU, its instruction timings differ wildly from common expectations and are more reflective of its 1990s-era design: While the V30MZ is an 80186-compatible CPU, its instruction timings differ wildly from common expectations and are more reflective of its 1990s-era design:
  
-  * ''MUL'' is very fast on this CPU, taking 3-4 cycles. As a result, "shift plus add" ladders will almost always be equal in performance on slower.+  * ''MUL'' is very fast on this CPU, taking 3-4 cycles. As a result, "shift plus add" ladders will almost always be slower or, at best, equal in performance.
   * Using ''XCHG'' over ''PUSH/POP'' (and ''XCHG AX, reg'' over ''MOV AX, reg'') is a popular pattern on the 8088/8086 due to the speed benefit. However, on the V30MZ, that is not the case:   * Using ''XCHG'' over ''PUSH/POP'' (and ''XCHG AX, reg'' over ''MOV AX, reg'') is a popular pattern on the 8088/8086 due to the speed benefit. However, on the V30MZ, that is not the case:
     * ''XCHG'' on V30MZ always takes 3 cycles.     * ''XCHG'' on V30MZ always takes 3 cycles.
wswan/guide/optimization_v30mz.1708200650.txt.gz · Last modified: by asie