; hash_init(context, alg);
hash_init:
    pop bc,de,hl
    push hl,de,bc
    ld a,l
    cp a, hash_algs_impl
    sbc a,a
    jr z, .error
    // if (! [l < hash_alg_count]); return false;
    ld h, 9
    mlt hl
    ld bc, hash_func_lookup
    add hl, bc
    ld iy, (hl)
    ld bc, 9
    ldir
    jp (iy)
.error:
    ld a, 0
    ret