rte_bitmap.h

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/*-
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 *
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 *       notice, this list of conditions and the following disclaimer.
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#ifndef __INCLUDE_RTE_BITMAP_H__
#define __INCLUDE_RTE_BITMAP_H__

#ifdef __cplusplus
extern "C" {
#endif

#include <rte_common.h>
#include <rte_debug.h>
#include <rte_memory.h>
#include <rte_branch_prediction.h>
#include <rte_prefetch.h>

#ifndef RTE_BITMAP_OPTIMIZATIONS
#define RTE_BITMAP_OPTIMIZATIONS                         1
#endif

/* Slab */
#define RTE_BITMAP_SLAB_BIT_SIZE                 64
#define RTE_BITMAP_SLAB_BIT_SIZE_LOG2            6
#define RTE_BITMAP_SLAB_BIT_MASK                 (RTE_BITMAP_SLAB_BIT_SIZE - 1)

/* Cache line (CL) */
#define RTE_BITMAP_CL_BIT_SIZE                   (RTE_CACHE_LINE_SIZE * 8)
#define RTE_BITMAP_CL_BIT_SIZE_LOG2              9
#define RTE_BITMAP_CL_BIT_MASK                   (RTE_BITMAP_CL_BIT_SIZE - 1)

#define RTE_BITMAP_CL_SLAB_SIZE                  (RTE_BITMAP_CL_BIT_SIZE / RTE_BITMAP_SLAB_BIT_SIZE)
#define RTE_BITMAP_CL_SLAB_SIZE_LOG2             3
#define RTE_BITMAP_CL_SLAB_MASK                  (RTE_BITMAP_CL_SLAB_SIZE - 1)

struct rte_bitmap {
        /* Context for array1 and array2 */
        uint64_t *array1;                        
        uint64_t *array2;                        
        uint32_t array1_size;                    
        uint32_t array2_size;                    
        /* Context for the "scan next" operation */
        uint32_t index1;  
        uint32_t offset1; 
        uint32_t index2;  
        uint32_t go2;     
        /* Storage space for array1 and array2 */
        uint8_t memory[0];
};

static inline void
__rte_bitmap_index1_inc(struct rte_bitmap *bmp)
{
        bmp->index1 = (bmp->index1 + 1) & (bmp->array1_size - 1);
}

static inline uint64_t
__rte_bitmap_mask1_get(struct rte_bitmap *bmp)
{
        return ((~1lu) << bmp->offset1);
}

static inline void
__rte_bitmap_index2_set(struct rte_bitmap *bmp)
{
        bmp->index2 = (((bmp->index1 << RTE_BITMAP_SLAB_BIT_SIZE_LOG2) + bmp->offset1) << RTE_BITMAP_CL_SLAB_SIZE_LOG2);
}

#if RTE_BITMAP_OPTIMIZATIONS

static inline int
rte_bsf64(uint64_t slab, uint32_t *pos)
{
        if (likely(slab == 0)) {
                return 0;
        }

        *pos = __builtin_ctzll(slab);
        return 1;
}

#else

static inline int
rte_bsf64(uint64_t slab, uint32_t *pos)
{
        uint64_t mask;
        uint32_t i;

        if (likely(slab == 0)) {
                return 0;
        }

        for (i = 0, mask = 1; i < RTE_BITMAP_SLAB_BIT_SIZE; i ++, mask <<= 1) {
                if (unlikely(slab & mask)) {
                        *pos = i;
                        return 1;
                }
        }

        return 0;
}

#endif

static inline uint32_t
__rte_bitmap_get_memory_footprint(uint32_t n_bits,
        uint32_t *array1_byte_offset, uint32_t *array1_slabs,
        uint32_t *array2_byte_offset, uint32_t *array2_slabs)
{
        uint32_t n_slabs_context, n_slabs_array1, n_cache_lines_context_and_array1;
        uint32_t n_cache_lines_array2;
        uint32_t n_bytes_total;

        n_cache_lines_array2 = (n_bits + RTE_BITMAP_CL_BIT_SIZE - 1) / RTE_BITMAP_CL_BIT_SIZE;
        n_slabs_array1 = (n_cache_lines_array2 + RTE_BITMAP_SLAB_BIT_SIZE - 1) / RTE_BITMAP_SLAB_BIT_SIZE;
        n_slabs_array1 = rte_align32pow2(n_slabs_array1);
        n_slabs_context = (sizeof(struct rte_bitmap) + (RTE_BITMAP_SLAB_BIT_SIZE / 8) - 1) / (RTE_BITMAP_SLAB_BIT_SIZE / 8);
        n_cache_lines_context_and_array1 = (n_slabs_context + n_slabs_array1 + RTE_BITMAP_CL_SLAB_SIZE - 1) / RTE_BITMAP_CL_SLAB_SIZE;
        n_bytes_total = (n_cache_lines_context_and_array1 + n_cache_lines_array2) * RTE_CACHE_LINE_SIZE;

        if (array1_byte_offset) {
                *array1_byte_offset = n_slabs_context * (RTE_BITMAP_SLAB_BIT_SIZE / 8);
        }
        if (array1_slabs) {
                *array1_slabs = n_slabs_array1;
        }
        if (array2_byte_offset) {
                *array2_byte_offset = n_cache_lines_context_and_array1 * RTE_CACHE_LINE_SIZE;
        }
        if (array2_slabs) {
                *array2_slabs = n_cache_lines_array2 * RTE_BITMAP_CL_SLAB_SIZE;
        }

        return n_bytes_total;
}

static inline void
__rte_bitmap_scan_init(struct rte_bitmap *bmp)
{
        bmp->index1 = bmp->array1_size - 1;
        bmp->offset1 = RTE_BITMAP_SLAB_BIT_SIZE - 1;
        __rte_bitmap_index2_set(bmp);
        bmp->index2 += RTE_BITMAP_CL_SLAB_SIZE;

        bmp->go2 = 0;
}

static inline uint32_t
rte_bitmap_get_memory_footprint(uint32_t n_bits) {
        /* Check input arguments */
        if (n_bits == 0) {
                return 0;
        }

        return __rte_bitmap_get_memory_footprint(n_bits, NULL, NULL, NULL, NULL);
}

static inline struct rte_bitmap *
rte_bitmap_init(uint32_t n_bits, uint8_t *mem, uint32_t mem_size)
{
        struct rte_bitmap *bmp;
        uint32_t array1_byte_offset, array1_slabs, array2_byte_offset, array2_slabs;
        uint32_t size;

        /* Check input arguments */
        if (n_bits == 0) {
                return NULL;
        }

        if ((mem == NULL) || (((uintptr_t) mem) & RTE_CACHE_LINE_MASK)) {
                return NULL;
        }

        size = __rte_bitmap_get_memory_footprint(n_bits,
                &array1_byte_offset, &array1_slabs,
                &array2_byte_offset, &array2_slabs);
        if (size < mem_size) {
                return NULL;
        }

        /* Setup bitmap */
        memset(mem, 0, size);
        bmp = (struct rte_bitmap *) mem;

        bmp->array1 = (uint64_t *) &mem[array1_byte_offset];
        bmp->array1_size = array1_slabs;
        bmp->array2 = (uint64_t *) &mem[array2_byte_offset];
        bmp->array2_size = array2_slabs;

        __rte_bitmap_scan_init(bmp);

        return bmp;
}

static inline int
rte_bitmap_free(struct rte_bitmap *bmp)
{
        /* Check input arguments */
        if (bmp == NULL) {
                return -1;
        }

        return 0;
}

static inline void
rte_bitmap_reset(struct rte_bitmap *bmp)
{
        memset(bmp->array1, 0, bmp->array1_size * sizeof(uint64_t));
        memset(bmp->array2, 0, bmp->array2_size * sizeof(uint64_t));
        __rte_bitmap_scan_init(bmp);
}

static inline void
rte_bitmap_prefetch0(struct rte_bitmap *bmp, uint32_t pos)
{
        uint64_t *slab2;
        uint32_t index2;

        index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
        slab2 = bmp->array2 + index2;
        rte_prefetch0((void *) slab2);
}

static inline uint64_t
rte_bitmap_get(struct rte_bitmap *bmp, uint32_t pos)
{
        uint64_t *slab2;
        uint32_t index2, offset2;

        index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
        offset2 = pos & RTE_BITMAP_SLAB_BIT_MASK;
        slab2 = bmp->array2 + index2;
        return ((*slab2) & (1lu << offset2));
}

static inline void
rte_bitmap_set(struct rte_bitmap *bmp, uint32_t pos)
{
        uint64_t *slab1, *slab2;
        uint32_t index1, index2, offset1, offset2;

        /* Set bit in array2 slab and set bit in array1 slab */
        index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
        offset2 = pos & RTE_BITMAP_SLAB_BIT_MASK;
        index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2);
        offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK;
        slab2 = bmp->array2 + index2;
        slab1 = bmp->array1 + index1;

        *slab2 |= 1lu << offset2;
        *slab1 |= 1lu << offset1;
}

static inline void
rte_bitmap_set_slab(struct rte_bitmap *bmp, uint32_t pos, uint64_t slab)
{
        uint64_t *slab1, *slab2;
        uint32_t index1, index2, offset1;

        /* Set bits in array2 slab and set bit in array1 slab */
        index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
        index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2);
        offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK;
        slab2 = bmp->array2 + index2;
        slab1 = bmp->array1 + index1;

        *slab2 |= slab;
        *slab1 |= 1lu << offset1;
}

static inline uint64_t
__rte_bitmap_line_not_empty(uint64_t *slab2)
{
        uint64_t v1, v2, v3, v4;

        v1 = slab2[0] | slab2[1];
        v2 = slab2[2] | slab2[3];
        v3 = slab2[4] | slab2[5];
        v4 = slab2[6] | slab2[7];
        v1 |= v2;
        v3 |= v4;

        return (v1 | v3);
}

static inline void
rte_bitmap_clear(struct rte_bitmap *bmp, uint32_t pos)
{
        uint64_t *slab1, *slab2;
        uint32_t index1, index2, offset1, offset2;

        /* Clear bit in array2 slab */
        index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
        offset2 = pos & RTE_BITMAP_SLAB_BIT_MASK;
        slab2 = bmp->array2 + index2;

        /* Return if array2 slab is not all-zeros */
        *slab2 &= ~(1lu << offset2);
        if (*slab2){
                return;
        }

        /* Check the entire cache line of array2 for all-zeros */
        index2 &= ~ RTE_BITMAP_CL_SLAB_MASK;
        slab2 = bmp->array2 + index2;
        if (__rte_bitmap_line_not_empty(slab2)) {
                return;
        }

        /* The array2 cache line is all-zeros, so clear bit in array1 slab */
        index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2);
        offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK;
        slab1 = bmp->array1 + index1;
        *slab1 &= ~(1lu << offset1);

        return;
}

static inline int
__rte_bitmap_scan_search(struct rte_bitmap *bmp)
{
        uint64_t value1;
        uint32_t i;

        /* Check current array1 slab */
        value1 = bmp->array1[bmp->index1];
        value1 &= __rte_bitmap_mask1_get(bmp);

        if (rte_bsf64(value1, &bmp->offset1)) {
                return 1;
        }

        __rte_bitmap_index1_inc(bmp);
        bmp->offset1 = 0;

        /* Look for another array1 slab */
        for (i = 0; i < bmp->array1_size; i ++, __rte_bitmap_index1_inc(bmp)) {
                value1 = bmp->array1[bmp->index1];

                if (rte_bsf64(value1, &bmp->offset1)) {
                        return 1;
                }
        }

        return 0;
}

static inline void
__rte_bitmap_scan_read_init(struct rte_bitmap *bmp)
{
        __rte_bitmap_index2_set(bmp);
        bmp->go2 = 1;
        rte_prefetch1((void *)(bmp->array2 + bmp->index2 + 8));
}

static inline int
__rte_bitmap_scan_read(struct rte_bitmap *bmp, uint32_t *pos, uint64_t *slab)
{
        uint64_t *slab2;

        slab2 = bmp->array2 + bmp->index2;
        for ( ; bmp->go2 ; bmp->index2 ++, slab2 ++, bmp->go2 = bmp->index2 & RTE_BITMAP_CL_SLAB_MASK) {
                if (*slab2) {
                        *pos = bmp->index2 << RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
                        *slab = *slab2;

                        bmp->index2 ++;
                        slab2 ++;
                        bmp->go2 = bmp->index2 & RTE_BITMAP_CL_SLAB_MASK;
                        return 1;
                }
        }

        return 0;
}

static inline int
rte_bitmap_scan(struct rte_bitmap *bmp, uint32_t *pos, uint64_t *slab)
{
        /* Return data from current array2 line if available */
        if (__rte_bitmap_scan_read(bmp, pos, slab)) {
                return 1;
        }

        /* Look for non-empty array2 line */
        if (__rte_bitmap_scan_search(bmp)) {
                __rte_bitmap_scan_read_init(bmp);
                __rte_bitmap_scan_read(bmp, pos, slab);
                return 1;
        }

        /* Empty bitmap */
        return 0;
}

#ifdef __cplusplus
}
#endif

#endif /* __INCLUDE_RTE_BITMAP_H__ */