ridiculousfish/libdivide

Health v2 · maintenance only

Flags: no_license

Adoption not part of the score

1348 stars · 98 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

libdivide is a single-header C/C++ library that replaces expensive integer division instructions with precomputed multiply-and-shift sequences, speeding up division by a runtime constant by up to 10x. It also supports SIMD vector division (SSE2, AVX2, AVX512, NEON, SVE) and runs on 8-bit microcontrollers like AVR.

Use cases

• speed up dividing many integers by a runtime constant
• optimize hash table bucket index computation
• accelerate scaling algorithms with integer division
• fast integer division in an interpreter loop
• divide SIMD vectors by a constant since SIMD lacks integer division
• fast division on microcontrollers without a hardware divider

When to choose

• you divide many numerators by the same runtime divisor in a hot loop
• you need SIMD integer division that hardware doesn't provide
• you target embedded hardware lacking a hardware divider
• you want a dependency-free, permissively licensed header-only optimization

When to avoid

• the divisor changes on every division (precomputation overhead dominates)
• you only divide by compile-time constants (compilers already optimize this)
• divisions are rare and not performance-critical

Facets

library · maturity stable

math developer-tools performance developer-tools cpp c cross-platform embedded header-only integer-division simd optimization branchless algorithms gpu

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