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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121// SPDX-License-Identifier: GPL-2.0-only/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
#include <linux/bits.h>
#define T 32#include "cnum_defs.h"#undef T
#define T 64#include "cnum_defs.h"#undef T
struct cnum32 cnum32_from_cnum64(struct cnum64 cnum){ if (cnum64_is_empty(cnum)) return CNUM32_EMPTY;
if (cnum.size >= U32_MAX) return (struct cnum32){ .base = 0, .size = U32_MAX }; else return (struct cnum32){ .base = (u32)cnum.base, .size = cnum.size };}
/* * Suppose 'a' and 'b' are laid out as follows: * * 64-bit number axis ---> * * N*2^32 (N+1)*2^32 (N+2)*2^32 (N+3)*2^32 * ||------|---|=====|-------||----------|=====|-------||----------|=====|----|--|| * | |< b >| |< b >| |< b >| | * | | | | * |<--+--------------------------- a ---------------------------+--->| * | | * |<-------------------------- t -------------------------->| * * In such a case it is possible to infer a more tight representation t * such that ∀ v ∈ a, (u32)v ∈ b: v ∈ t. */struct cnum64 cnum64_cnum32_intersect(struct cnum64 a, struct cnum32 b){ /* * To simplify reasoning, rotate the circles so that [virtual] a1 starts * at u32 boundary, b1 represents b in this new frame of reference. */ struct cnum32 b1 = { b.base - (u32)a.base, b.size }; struct cnum64 t = a; u64 d, b1_max;
if (cnum64_is_empty(a) || cnum32_is_empty(b)) return CNUM64_EMPTY;
if (cnum32_urange_overflow(b1)) { b1_max = (u32)b1.base + (u32)b1.size; /* overflow here is fine and necessary */ if ((u32)a.size > b1_max && (u32)a.size < b1.base) { /* * N*2^32 (N+1)*2^32 * ||=====|------------|=====||=====|---------|---|=====|| * |b1 ->| |<- b1||b1 ->| | |<- b1| * |<----------------- a1 ------------------>| * |<-------------- t ------------>|<-- d -->| (after adjustment) * ^ * b1_max */ d = (u32)a.size - b1_max; t.size -= d; } else { /* * No adjustments possible in the following cases: * * ||=====|------------|=====||===|=|-------------|=|===|| * |b1 ->| |<- b1||b1 +>| |<+ b1| * |<----------------- a1 ------>| | * |<----------------- (or) a1 ------------------->| */ } } else { if (t.size < b1.base) /* * N*2^32 (N+1)*2^32 * ||----------|--|=======|--||------> * |<-- a1 -->| |<- b ->| */ return CNUM64_EMPTY; /* * N*2^32 (N+1)*2^32 * ||-------------|========|-||-----| -------|========|-|| * | |<- b1 ->| | |<- b1 ->| * |<------------+ a1 ------------>| * |<------ t ------>| (after adjustment) */ t.base += b1.base; t.size -= b1.base; b1_max = b1.base + b1.size; d = 0; if ((u32)a.size < b1.base) /* * N*2^32 (N+1)*2^32 * ||-------------|========|-||------|-------|========|-|| * | |<- b1 ->| | |<- b1 ->| * |<------------+-- a1 --+-------->| * |<- t ->|<-- d -->| (after adjustment) */ d = (u32)a.size + (BIT_ULL(32) - b1_max); else if ((u32)a.size >= b1_max) /* * N*2^32 (N+1)*2^32 * ||--|========|------------||--|========|-------|-----|| * | |<- b1 ->| |<- b1 ->| | * |<-+------------------ a1 ------------+------>| * |<-------------- t --------------->|<- d ->| (after adjustment) */ d = (u32)a.size - b1_max; if (t.size < d) return CNUM64_EMPTY; t.size -= d; } return t;}