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--- wswan:guide:optimization [2025/12/31 12:42] – created asie
+++ wswan:guide:optimization [2025/12/31 12:50] (current) – [Optimizing for memory usage] asie
@@ Line 1: / Line 1: @@
-====== Writing optimized code ======
+====== Optimizing programs ======
 This page serves as a loose list of advice for getting the most out of the WonderSwan.
-===== Optimizing for speed =====
+===== Optimizing C code =====
+==== Optimizing for code speed ====
 To optimize for speed, compile your code with ''%%-O2%%''.
-===== Optimizing for size =====
+==== Optimizing for code size ====
 To optimize for size, compile your code with ''%%-Os%%''.
-===== Optimizing for memory usage =====
+==== Optimizing for memory usage ====
   * For data stored in RAM, use the smallest type possible.
     * Exception: For argument passing, there is little reason to prefer ''%%char%%'' over ''%%int%%'' - the stack is always aligned to 2 bytes.
-  * By default, GCC allows function call arguments to accumulate on the stack, then pops them all at once. To reduce stack usage at the cost of a larger and slightly slower program, compile your code with ''%%fno-defer-pop%%''.
+  * By default, GCC allows function call arguments to accumulate on the stack, then pops them all at once. To reduce peak stack usage at the cost of a larger and slightly slower program, compile your code with ''%%-fno-defer-pop%%''.
 ===== Optimizing assembly code =====
+==== Optimizing for speed ====
 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:
@@ Line 29: / Line 33: @@
 You can study the instruction timings in detail on [[https://ws.nesdev.org/wiki/NEC_V30MZ_instruction_set|the WSdev wiki]].
+There are also some additional tricks you can take advantage of:
+  * Avoid far calls between functions - branches are expensive, and far branches are significantly more expensive. If you're calling a far function from another far function in the same section, use the ''%%IA16_CALL_LOCAL%%'' macro over a far call to save a few cycles.
+  * Try word-aligning loop labels by prepending them with ''%%.align 2, 0x90%%'' - this generates a NOP opcode if necessary. This may help a little.