/* store_v3.c -- the kernel's block subsystem as the chains behind a storage
 * port.  docs/v4.0.0/MESH.md 8.4, docs/v4.0.0/V3-PARITY.md 1d.
 *
 * A chain is a blk_chain_t (v3/include/block_subsystem.h).  Every block goes
 * through v3's own calls, so the header, the allocation map, the block
 * cards and relocation are v3's, as they were.  Who may have a block is not
 * checked here yet (MESH.md 8.5).
 *
 * This is the one file of v4's that includes v3's headers.
 */
#include "v4/storage.h"
#include "block_subsystem.h"

static int v3_read(void *chain, uint32_t block, unsigned char *bytes)
{
    blk_chain_t *was = blk_chain_select((blk_chain_t *)chain);
    int status = V4_STORE_RANGE;
    unsigned i;

    if (blk_is_valid(block)) {
        const uint8_t *b = blk_get_buffer(block, 0);
        status = b ? V4_STORE_OK : V4_STORE_REFUSED;
        if (b) for (i = 0; i < V4_STORE_BYTES; i++) bytes[i] = b[i];
    }
    blk_chain_select(was);
    return status;
}

static int v3_write(void *chain, uint32_t block, const unsigned char *bytes)
{
    blk_chain_t *was = blk_chain_select((blk_chain_t *)chain);
    int status = V4_STORE_RANGE;
    unsigned i;

    if (blk_is_valid(block)) {
        uint8_t *b = blk_get_buffer(block, 1);
        status = V4_STORE_REFUSED;
        if (b) {
            for (i = 0; i < V4_STORE_BYTES; i++) b[i] = bytes[i];
            if (blk_update(block) == BLK_OK && blk_flush(block) == BLK_OK) status = V4_STORE_OK;
        }
    }
    blk_chain_select(was);
    return status;
}

static uint32_t v3_blocks(void *chain)
{
    blk_chain_t *was = blk_chain_select((blk_chain_t *)chain);
    uint32_t n = blk_get_total_blocks();
    blk_chain_select(was);
    return n;
}

const v4_store_ops v4_store_v3 = { v3_read, v3_write, v3_blocks };