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Add Bitwise Operators #21

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Add Bitwise Operators #21

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ac9cfc9
Add Bitwise Operators
tapple Dec 21, 2025
eb69c06
change bit32.band to bit32.btest. It's more commonly correct
tapple Jan 7, 2026
64f29f5
typo in lshift
tapple Jan 8, 2026
78e6bf1
Merge remote-tracking branch 'origin/main' into patch-2
tapple Apr 28, 2026
8cdd7ba
Fix review comments
tapple May 10, 2026
e333a7b
more clarification about `bit32.band`
tapple May 10, 2026
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6 changes: 6 additions & 0 deletions src/content/docs/script/learn-lua/from-lsl.mdx
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Expand Up @@ -93,6 +93,12 @@ local items: {number} = {1, 2, 3} -- tables, not lists
| Power | `llPow(2, 3)` | `2 ^ 3` | Native operator |
| Integer division | `7 / 4` → `1` | `7 // 4` → `1` | Use `//` not `/` |
| String length | `llStringLength(s)` | `#s` | Native operator |
| Bitwise AND | `llGetAgentInfo(id) & AGENT_TYPING` | `bit32.btest(ll.GetAgentInfo(id), AGENT_TYPING)` | No `&` operator |
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@monty-linden monty-linden May 10, 2026

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btest() gives a boolean result - band() is wanted here

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@tapple tapple May 10, 2026

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in my experience, band is more a footgun, because, most of the time, you want to put it in an if block. and only btest makes sense in an if statement. (I even wrote a linter rule about this because it bit me so hard: luau-lang/luau#2184)

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@tapple tapple May 10, 2026

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added a note

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@monty-linden monty-linden May 10, 2026

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Perhaps for idiomatic Lua, there are two modes of expression for bitwise AND:

  • b32.band() where the resulting value is important
  • (b32.btest() [and/or] b32.btest() [and/or] b32.btest() ...) where a conditional test is being constructed. Test varies whether you want all mask bits set or any mask bit set.

Anyway, changes accepted.

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@tapple tapple May 10, 2026

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btest seems to be the one that matches the main use of & in LSL:

> flags = bit32.bor(CONTROL_UP, CONTROL_LEFT)
> bit32.btest(flags, CONTROL_UP)
true
> bit32.btest(flags, CONTROL_LEFT)
true
> bit32.btest(flags, CONTROL_DOWN)
false

| Bitwise OR | `PASSIVE | SCRIPTED` | `bit32.bor(PASSIVE | SCRIPTED)` | No `|` operator |
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@monty-linden monty-linden May 10, 2026

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Should be 'bit32.bor(PASSIVE, SCRIPTED)

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@tapple tapple May 10, 2026

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fixed

| Bitwise NOT | `~0` | `bit32.bnot(0)` | No `~` operator |
| Bitwise eXclusive OR | `6 ^ 3` | `bit32.bxor(6, 3)` | `^` means Power instead |
| Bitwise Shift Left | `1 << 2` | `bit32.lshift(1, 2)` | No `<<` operator |
| Bitwise Shift Right | `0x80000000 >> 2` | `bit32.arshift(0x80000000, 2)` | No `>>` operator |
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@monty-linden monty-linden May 10, 2026

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In LSL, this is an arithmetic shift on signed, 32-bit value, not bitwise on unsigned. '0x80000000 >> 2' produces the result -536870912. In Luau, 'bit32.arshift(0x80000000, 2)' is a pseudo-signed operator producing the result 3758096384. This is bit correct though not value correct but that's expected here. May wish to warn the reader.

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@tapple tapple May 10, 2026

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### Control Flow

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