static unsigned int BN_STACK_pop(BN_STACK *st)
{
    return st->indexes[--(st->depth)];
}
['static int test_gf2m_sqr(void)\n{\n    BIGNUM *a = NULL, *b[2] = {NULL,NULL}, *c = NULL, *d = NULL;\n    int i, j, st = 0;\n    if (!TEST_ptr(a = BN_new())\n            || !TEST_ptr(b[0] = BN_new())\n            || !TEST_ptr(b[1] = BN_new())\n            || !TEST_ptr(c = BN_new())\n            || !TEST_ptr(d = BN_new()))\n        goto err;\n    BN_GF2m_arr2poly(p0, b[0]);\n    BN_GF2m_arr2poly(p1, b[1]);\n    for (i = 0; i < NUM0; i++) {\n        BN_bntest_rand(a, 1024, 0, 0);\n        for (j = 0; j < 2; j++) {\n            BN_GF2m_mod_sqr(c, a, b[j], ctx);\n            BN_copy(d, a);\n            BN_GF2m_mod_mul(d, a, d, b[j], ctx);\n            BN_GF2m_add(d, c, d);\n            if (!TEST_BN_eq_zero(d))\n                goto err;\n        }\n    }\n    st = 1;\n err:\n    BN_free(a);\n    BN_free(b[0]);\n    BN_free(b[1]);\n    BN_free(c);\n    BN_free(d);\n    return st;\n}', 'int BN_GF2m_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)\n{\n    int ret = 0;\n    const int max = BN_num_bits(p) + 1;\n    int *arr = NULL;\n    bn_check_top(a);\n    bn_check_top(p);\n    if ((arr = OPENSSL_malloc(sizeof(*arr) * max)) == NULL)\n        goto err;\n    ret = BN_GF2m_poly2arr(p, arr, max);\n    if (!ret || ret > max) {\n        BNerr(BN_F_BN_GF2M_MOD_SQR, BN_R_INVALID_LENGTH);\n        goto err;\n    }\n    ret = BN_GF2m_mod_sqr_arr(r, a, arr, ctx);\n    bn_check_top(r);\n err:\n    OPENSSL_free(arr);\n    return ret;\n}', 'int BN_GF2m_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,\n                    const BIGNUM *p, BN_CTX *ctx)\n{\n    int ret = 0;\n    const int max = BN_num_bits(p) + 1;\n    int *arr = NULL;\n    bn_check_top(a);\n    bn_check_top(b);\n    bn_check_top(p);\n    if ((arr = OPENSSL_malloc(sizeof(*arr) * max)) == NULL)\n        goto err;\n    ret = BN_GF2m_poly2arr(p, arr, max);\n    if (!ret || ret > max) {\n        BNerr(BN_F_BN_GF2M_MOD_MUL, BN_R_INVALID_LENGTH);\n        goto err;\n    }\n    ret = BN_GF2m_mod_mul_arr(r, a, b, arr, ctx);\n    bn_check_top(r);\n err:\n    OPENSSL_free(arr);\n    return ret;\n}', 'int BN_GF2m_mod_sqr_arr(BIGNUM *r, const BIGNUM *a, const int p[],\n                        BN_CTX *ctx)\n{\n    int i, ret = 0;\n    BIGNUM *s;\n    bn_check_top(a);\n    BN_CTX_start(ctx);\n    if ((s = BN_CTX_get(ctx)) == NULL)\n        goto err;\n    if (!bn_wexpand(s, 2 * a->top))\n        goto err;\n    for (i = a->top - 1; i >= 0; i--) {\n        s->d[2 * i + 1] = SQR1(a->d[i]);\n        s->d[2 * i] = SQR0(a->d[i]);\n    }\n    s->top = 2 * a->top;\n    bn_correct_top(s);\n    if (!BN_GF2m_mod_arr(r, s, p))\n        goto err;\n    bn_check_top(r);\n    ret = 1;\n err:\n    BN_CTX_end(ctx);\n    return ret;\n}', 'void BN_CTX_start(BN_CTX *ctx)\n{\n    CTXDBG("ENTER BN_CTX_start()", ctx);\n    if (ctx->err_stack || ctx->too_many)\n        ctx->err_stack++;\n    else if (!BN_STACK_push(&ctx->stack, ctx->used)) {\n        BNerr(BN_F_BN_CTX_START, BN_R_TOO_MANY_TEMPORARY_VARIABLES);\n        ctx->err_stack++;\n    }\n    CTXDBG("LEAVE BN_CTX_start()", ctx);\n}', 'void BN_CTX_end(BN_CTX *ctx)\n{\n    CTXDBG("ENTER BN_CTX_end()", ctx);\n    if (ctx->err_stack)\n        ctx->err_stack--;\n    else {\n        unsigned int fp = BN_STACK_pop(&ctx->stack);\n        if (fp < ctx->used)\n            BN_POOL_release(&ctx->pool, ctx->used - fp);\n        ctx->used = fp;\n        ctx->too_many = 0;\n    }\n    CTXDBG("LEAVE BN_CTX_end()", ctx);\n}', 'static unsigned int BN_STACK_pop(BN_STACK *st)\n{\n    return st->indexes[--(st->depth)];\n}']