SRWLOCK

Structure SRWLOCK uses pointer-sized storage with embedded flags in the low bits.

Syntax

typedef struct _SRWLOCK {
    PVOID Ptr;
} SRWLOCK, *PSRWLOCK;

State Encoding

The Ptr field encodes both state flags and wait block pointers:

Bit 0 — SRWLOCK_OWNED

Lock is currently owned.

Bit 1 — SRWLOCK_CONTENDED

One or more threads are queued.

Bit 2 — SRWLOCK_SHARED

Lock is held in shared mode.

Bit 3 — SRWLOCK_CONTENTION_LOCK

Wait‑block list is being modified.

Bits 4+

Shared reference count or wait‑block pointer.

Requirements