/* blocks.c -- the kernel serves a node's block requests.  See blocks.h.
 *
 * This is the one file of v4's that includes v3's headers: every block goes
 * through v3's own calls.
 */
#include "v4/blocks.h"
#include "block_subsystem.h"

int v4_blocks_serve(v4_node *n, v4_cell request)
{
    v4_cell addr, num;
    uint32_t block;
    uint8_t *b;
    unsigned i;
    int status;

    if (request != V4_REQ_BLOCK_READ && request != V4_REQ_BLOCK_WRITE) return 0;
    addr = v4_dstack_pop(&n->ds);
    num = v4_dstack_pop(&n->ds);
    block = (uint32_t)num;

    if (!v4_node_addr_ok(addr) || !v4_node_addr_ok(addr + (v4_cell)(V4_BLOCK_CELLS - 1u))) {
        status = V4_BLOCK_REFUSED;
    } else if (num < 1 || (uint64_t)num > 0xFFFFFFFFull || !blk_is_valid(block)) {
        status = V4_BLOCK_RANGE;
    } else if (request == V4_REQ_BLOCK_READ) {
        b = blk_get_buffer(block, 0);
        status = b ? V4_BLOCK_OK : V4_BLOCK_REFUSED;
        if (b)
            for (i = 0; i < V4_BLOCK_CELLS; i++)
                n->mem[addr + (v4_cell)i] = (v4_cell)((v4_ucell)b[4u * i] | ((v4_ucell)b[4u * i + 1u] << 8)
                                                     | ((v4_ucell)b[4u * i + 2u] << 16) | ((v4_ucell)b[4u * i + 3u] << 24));
    } else {
        b = blk_get_buffer(block, 1);
        status = V4_BLOCK_REFUSED;
        if (b) {
            for (i = 0; i < V4_BLOCK_CELLS; i++) {
                v4_ucell w = (v4_ucell)n->mem[addr + (v4_cell)i];
                b[4u * i] = (uint8_t)(w & 0xFFu);
                b[4u * i + 1u] = (uint8_t)((w >> 8) & 0xFFu);
                b[4u * i + 2u] = (uint8_t)((w >> 16) & 0xFFu);
                b[4u * i + 3u] = (uint8_t)((w >> 24) & 0xFFu);
            }
            if (blk_update(block) == BLK_OK && blk_flush(block) == BLK_OK) status = V4_BLOCK_OK;
        }
    }
    v4_dstack_push(&n->ds, (v4_cell)status);
    return 1;
}