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| author | Rangi <remy.oukaour+rangi42@gmail.com> | 2021-03-12 14:05:16 -0500 |
|---|---|---|
| committer | Rangi <remy.oukaour+rangi42@gmail.com> | 2021-03-12 14:05:16 -0500 |
| commit | f9f1695821cdd632761c9a487bb710d61a3fbc7f (patch) | |
| tree | 73441df132acfba437e655c96e13768ae8218359 /Optimizing-assembly-code.md | |
| parent | abbcc567a1f93a078ab297d5238afe27a87cbd63 (diff) | |
Conditional return
Diffstat (limited to 'Optimizing-assembly-code.md')
| -rw-r--r-- | Optimizing-assembly-code.md | 32 |
1 files changed, 28 insertions, 4 deletions
diff --git a/Optimizing-assembly-code.md b/Optimizing-assembly-code.md index d18495f..51c512d 100644 --- a/Optimizing-assembly-code.md +++ b/Optimizing-assembly-code.md @@ -56,8 +56,9 @@ WikiTI's advice fully applies here: - [Inlining](#inlining) - [Fallthrough](#fallthrough) - [Conditional fallthrough](#conditional-fallthrough) - - [Call a function depending on a flag](#call-a-function-depending-on-a-flag) - - [Call `rst $38` depending on a flag](#call-rst-38-depending-on-a-flag) + - [Conditional return](#conditional-return) + - [Conditional call](#conditional-call) + - [Conditional `rst $38`](#conditional-rst-38) - [Jump and lookup tables](#jump-and-lookup-tables) - [Chain comparisons](#chain-comparisons) @@ -1471,7 +1472,30 @@ But do: ``` -### Call a function depending on a flag +## Conditional return + +(The example uses `z`, but `nz`, `c`, or `nc` would also work.) + +Don't do: + +```asm + ; 3 bytes, 3 or 6 cycles + jr z, .skip + ret +.skip + ... +``` + +But do: + +```asm + ; 1 byte, 5 or 2 cycles + ret nz + ... +``` + + +### Conditional call (The example uses `z`, but `nz`, `c`, or `nc` would also work.) @@ -1508,7 +1532,7 @@ But do: ``` -### Call `rst $38` depending on a flag +### Conditional `rst $38` (The example uses `z`, but `nz`, `c`, or `nc` would also work.) |