cache_coherency_shared_t Struct Reference

Cross-CPU message struct backed by a fixed non-cacheable SRAM address. More...

#include <cache_coherency_shared.h>

Data Fields
volatile uint32_t	ping_seq
	CPU0 increments after writing payload.
volatile uint32_t	pong_seq
	CPU1 sets to match ping_seq after reply.
volatile uint32_t	ping_payload
	CPU0 writes ping_base + r, CPU1 reads.
volatile uint32_t	pong_payload
	CPU1 writes ping_payload + delta.

Detailed Description

Cross-CPU message struct backed by a fixed non-cacheable SRAM address.

Every field is volatile so the compiler emits a real memory access each loop iteration on both cores. The struct is small (16 bytes) and pinned at a 32-byte-aligned address, so with the M85 D-cache enabled it occupies a single cache line – except the MPU marks that line's region non-cacheable, so the accesses go straight to SRAM and stay coherent with the cacheless M33.

Invariant

pong_seq only ever lags ping_seq by 0 or 1.

Both sequence counters monotonically increase.

See also

cache_coherency_shared

Since

0.1.0

Definition at line 132 of file cache_coherency_shared.h.

Field Documentation

ping_payload

volatile uint32_t cache_coherency_shared_t::ping_payload

CPU0 writes ping_base + r, CPU1 reads.

Definition at line 135 of file cache_coherency_shared.h.

Referenced by internal_cpu1_main(), internal_round(), and main().

ping_seq

volatile uint32_t cache_coherency_shared_t::ping_seq

CPU0 increments after writing payload.

Definition at line 133 of file cache_coherency_shared.h.

Referenced by internal_cpu1_main(), internal_round(), and main().

pong_payload

volatile uint32_t cache_coherency_shared_t::pong_payload

CPU1 writes ping_payload + delta.

Definition at line 136 of file cache_coherency_shared.h.

Referenced by internal_cpu1_main(), internal_round(), and main().

pong_seq

volatile uint32_t cache_coherency_shared_t::pong_seq

CPU1 sets to match ping_seq after reply.

Definition at line 134 of file cache_coherency_shared.h.

Referenced by internal_cpu1_main(), internal_wait_for_pong(), and main().

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The documentation for this struct was generated from the following file:

• examples/ek_ra8d2/hw_validated/hil/cache_coherency_hil/inc/cache_coherency_shared.h