/*
 * Compile-out HW debug timeline (bench only).
 *
 *   make HW_DEBUG=1   → -DPOG422_HW_DEBUG=1
 *   make              → all macros compile to nothing (prod)
 *
 * No runtime is_debug checks on hot paths.
 */
#ifndef POG422_HW_DEBUG_H
#define POG422_HW_DEBUG_H

#include <stdint.h>
#include <string.h>
#include <time.h>

#ifndef POG422_HW_DEBUG
#define POG422_HW_DEBUG 0
#endif

/* Event types (userspace ring + IPC). GPIO5_* only from driver USB-INT drain. */
enum {
    POG422_HWDBG_HS_RISE = 1,
    POG422_HWDBG_HS_FALL = 2,
    POG422_HWDBG_RX_CHUNK = 3,
    POG422_HWDBG_TX_BULK_START = 4,
    POG422_HWDBG_TX_BULK_DONE = 5,
    POG422_HWDBG_DE_ON = 6,
    POG422_HWDBG_DE_OFF = 7,
    POG422_HWDBG_TEMT = 8,
    POG422_HWDBG_GPIO1_EDGE = 9,
    POG422_HWDBG_GPIO5_EDGE = 10,
    POG422_HWDBG_MARK = 11,
    POG422_HWDBG_COPPER = 12,
};

#ifndef POG422_HWDBG_RING_MAX
#define POG422_HWDBG_RING_MAX 512u
#endif

typedef struct __attribute__((packed)) {
    uint64_t t_mono_ns;
    uint8_t type;
    uint8_t _pad;
    uint16_t a; /* first byte / gpio flags / phase */
    uint32_t b; /* len / gpio_stat / fifo */
} pog422_hwdbg_sample_t;

typedef struct __attribute__((packed)) {
    uint32_t n;
    uint32_t dropped;
    /* n × pog422_hwdbg_sample_t follows in IPC */
} pog422_ipc_hwdbg_hdr_t;

#if POG422_HW_DEBUG

#define HWDBG_ENABLED 1

typedef struct {
    pog422_hwdbg_sample_t samples[POG422_HWDBG_RING_MAX];
    uint32_t head; /* next write */
    uint32_t count;
    uint32_t dropped;
} pog422_hwdbg_ring_t;

static inline uint64_t pog422_hwdbg_mono_ns(void)
{
    struct timespec ts;
    clock_gettime(CLOCK_MONOTONIC, &ts);
    return (uint64_t)ts.tv_sec * 1000000000ull + (uint64_t)ts.tv_nsec;
}

static inline void pog422_hwdbg_ring_init(pog422_hwdbg_ring_t *r)
{
    if (!r) {
        return;
    }
    memset(r, 0, sizeof(*r));
}

static inline void pog422_hwdbg_emit(
    pog422_hwdbg_ring_t *r,
    uint8_t type,
    uint16_t a,
    uint32_t b,
    uint64_t t_mono_ns
)
{
    pog422_hwdbg_sample_t *s;

    if (!r) {
        return;
    }
    s = &r->samples[r->head];
    s->t_mono_ns = t_mono_ns ? t_mono_ns : pog422_hwdbg_mono_ns();
    s->type = type;
    s->_pad = 0;
    s->a = a;
    s->b = b;
    r->head = (r->head + 1u) % POG422_HWDBG_RING_MAX;
    if (r->count < POG422_HWDBG_RING_MAX) {
        r->count++;
    } else {
        r->dropped++;
    }
}

/* Copy chronological samples into out[]; returns n written. Clears ring. */
static inline uint32_t pog422_hwdbg_ring_drain(
    pog422_hwdbg_ring_t *r,
    pog422_hwdbg_sample_t *out,
    uint32_t max_out,
    uint32_t *dropped_out
)
{
    uint32_t n;
    uint32_t start;
    uint32_t i;

    if (!r || !out || max_out == 0u) {
        if (dropped_out) {
            *dropped_out = r ? r->dropped : 0u;
        }
        return 0u;
    }
    n = r->count;
    if (n > max_out) {
        n = max_out;
    }
    start = (r->head + POG422_HWDBG_RING_MAX - r->count) % POG422_HWDBG_RING_MAX;
    for (i = 0; i < n; i++) {
        out[i] = r->samples[(start + i) % POG422_HWDBG_RING_MAX];
    }
    if (dropped_out) {
        *dropped_out = r->dropped;
    }
    r->head = 0;
    r->count = 0;
    r->dropped = 0;
    return n;
}

#define HWDBG_EMIT(ring, type, a, b) \
    pog422_hwdbg_emit((ring), (uint8_t)(type), (uint16_t)(a), (uint32_t)(b), 0ull)

#define HWDBG_EMIT_AT(ring, type, a, b, tns) \
    pog422_hwdbg_emit((ring), (uint8_t)(type), (uint16_t)(a), (uint32_t)(b), (uint64_t)(tns))

#else /* !POG422_HW_DEBUG */

#define HWDBG_ENABLED 0

typedef struct {
    uint8_t _unused;
} pog422_hwdbg_ring_t;

static inline void pog422_hwdbg_ring_init(pog422_hwdbg_ring_t *r)
{
    (void)r;
}

static inline void pog422_hwdbg_emit(
    pog422_hwdbg_ring_t *r,
    uint8_t type,
    uint16_t a,
    uint32_t b,
    uint64_t t_mono_ns
)
{
    (void)r;
    (void)type;
    (void)a;
    (void)b;
    (void)t_mono_ns;
}

#define HWDBG_EMIT(ring, type, a, b) ((void)0)
#define HWDBG_EMIT_AT(ring, type, a, b, tns) ((void)0)

static inline uint32_t pog422_hwdbg_ring_drain(
    pog422_hwdbg_ring_t *r,
    pog422_hwdbg_sample_t *out,
    uint32_t max_out,
    uint32_t *dropped_out
)
{
    (void)r;
    (void)out;
    (void)max_out;
    if (dropped_out) {
        *dropped_out = 0u;
    }
    return 0u;
}

#endif /* POG422_HW_DEBUG */

#endif /* POG422_HW_DEBUG_H */