platform

mantis-platform

Platform abstractions for the Mantis SDK, achieving full parity with Constantine's platforms/ module.

Provides constant-time types, extended-precision intrinsics, cycle counters, and ISA-specific primitives — all no_std compatible.

Module Layout

constant_time/   Ct<T>, CTBool<T>, constant-time arithmetic, multiplexers,
                 constant-time division
intrinsics/      Extended-precision arithmetic (wide mul, add-with-carry,
                 sub-with-borrow), prefetch hints, copy policies
bithacks         Bit manipulation utilities (clz, ctz, popcount, byte-swap)
config           Compile-time platform configuration (word size, endianness,
                 feature detection flags)
metering/        CycleCounter trait, Measurement wrapper,
                 platform-specific counter implementations
isa_x86/         x86_64 assembler types, CPUID detection, RDTSC counter
isa_arm64/       ARM64 assembler types, condition codes,
                 Kperf/PMU cycle counters
pad              CachePadded<T> — 128-byte alignment to prevent false sharing
cpudetect        CPU model name detection (used in benchmark reports)

Feature Flags

Flag	Default	Effect
std	off	Enable std-dependent paths (CPU name detection, OS counters)
asm	off	Enable inline assembly paths (RDTSC, ARM PMU, wide-mul asm)
nightly	off	Enable nightly-only intrinsics and unstable features

The crate is no_std by default. Enable std for benchmark tooling and OS integration. Enable asm for production-grade cycle counters and hot-path assembly.

Usage

use mantis_platform::pad::CachePadded;
use mantis_platform::metering::{CycleCounter, Measurement};

// Cache-line isolate a hot value
let head = CachePadded::new(0u64);

// Read a cycle counter
let start = Measurement::now();
// ... work ...
let elapsed = start.elapsed();

For constant-time operations:

use mantis_platform::constant_time::{Ct, CTBool};

let a = Ct::new(42u64);
let b = Ct::new(42u64);
let equal: CTBool<u64> = a.ct_eq(b);

Design Notes

• No runtime dispatch in hot paths — platform selection is cfg(target_arch)
• Assembly paths live in isa_x86/assembly/ and isa_arm64/assembly/
• All platform variants are differential-tested against the portable baseline
• Unsafe code is isolated in raw submodules with // SAFETY: comments