static unsigned int BN_STACK_pop(BN_STACK *st)
{
    return st->indexes[--(st->depth)];
}
['int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,\n                     const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m,\n                     BN_CTX *ctx, BN_MONT_CTX *in_mont)\n{\n    int i, j, bits, b, bits1, bits2, ret =\n        0, wpos1, wpos2, window1, window2, wvalue1, wvalue2;\n    int r_is_one = 1;\n    BIGNUM *d, *r;\n    const BIGNUM *a_mod_m;\n    BIGNUM *val1[TABLE_SIZE], *val2[TABLE_SIZE];\n    BN_MONT_CTX *mont = NULL;\n    bn_check_top(a1);\n    bn_check_top(p1);\n    bn_check_top(a2);\n    bn_check_top(p2);\n    bn_check_top(m);\n    if (!(m->d[0] & 1)) {\n        BNerr(BN_F_BN_MOD_EXP2_MONT, BN_R_CALLED_WITH_EVEN_MODULUS);\n        return 0;\n    }\n    bits1 = BN_num_bits(p1);\n    bits2 = BN_num_bits(p2);\n    if ((bits1 == 0) && (bits2 == 0)) {\n        ret = BN_one(rr);\n        return ret;\n    }\n    bits = (bits1 > bits2) ? bits1 : bits2;\n    BN_CTX_start(ctx);\n    d = BN_CTX_get(ctx);\n    r = BN_CTX_get(ctx);\n    val1[0] = BN_CTX_get(ctx);\n    val2[0] = BN_CTX_get(ctx);\n    if (val2[0] == NULL)\n        goto err;\n    if (in_mont != NULL)\n        mont = in_mont;\n    else {\n        if ((mont = BN_MONT_CTX_new()) == NULL)\n            goto err;\n        if (!BN_MONT_CTX_set(mont, m, ctx))\n            goto err;\n    }\n    window1 = BN_window_bits_for_exponent_size(bits1);\n    window2 = BN_window_bits_for_exponent_size(bits2);\n    if (a1->neg || BN_ucmp(a1, m) >= 0) {\n        if (!BN_mod(val1[0], a1, m, ctx))\n            goto err;\n        a_mod_m = val1[0];\n    } else\n        a_mod_m = a1;\n    if (BN_is_zero(a_mod_m)) {\n        BN_zero(rr);\n        ret = 1;\n        goto err;\n    }\n    if (!BN_to_montgomery(val1[0], a_mod_m, mont, ctx))\n        goto err;\n    if (window1 > 1) {\n        if (!BN_mod_mul_montgomery(d, val1[0], val1[0], mont, ctx))\n            goto err;\n        j = 1 << (window1 - 1);\n        for (i = 1; i < j; i++) {\n            if (((val1[i] = BN_CTX_get(ctx)) == NULL) ||\n                !BN_mod_mul_montgomery(val1[i], val1[i - 1], d, mont, ctx))\n                goto err;\n        }\n    }\n    if (a2->neg || BN_ucmp(a2, m) >= 0) {\n        if (!BN_mod(val2[0], a2, m, ctx))\n            goto err;\n        a_mod_m = val2[0];\n    } else\n        a_mod_m = a2;\n    if (BN_is_zero(a_mod_m)) {\n        BN_zero(rr);\n        ret = 1;\n        goto err;\n    }\n    if (!BN_to_montgomery(val2[0], a_mod_m, mont, ctx))\n        goto err;\n    if (window2 > 1) {\n        if (!BN_mod_mul_montgomery(d, val2[0], val2[0], mont, ctx))\n            goto err;\n        j = 1 << (window2 - 1);\n        for (i = 1; i < j; i++) {\n            if (((val2[i] = BN_CTX_get(ctx)) == NULL) ||\n                !BN_mod_mul_montgomery(val2[i], val2[i - 1], d, mont, ctx))\n                goto err;\n        }\n    }\n    r_is_one = 1;\n    wvalue1 = 0;\n    wvalue2 = 0;\n    wpos1 = 0;\n    wpos2 = 0;\n    if (!BN_to_montgomery(r, BN_value_one(), mont, ctx))\n        goto err;\n    for (b = bits - 1; b >= 0; b--) {\n        if (!r_is_one) {\n            if (!BN_mod_mul_montgomery(r, r, r, mont, ctx))\n                goto err;\n        }\n        if (!wvalue1)\n            if (BN_is_bit_set(p1, b)) {\n                i = b - window1 + 1;\n                while (!BN_is_bit_set(p1, i))\n                    i++;\n                wpos1 = i;\n                wvalue1 = 1;\n                for (i = b - 1; i >= wpos1; i--) {\n                    wvalue1 <<= 1;\n                    if (BN_is_bit_set(p1, i))\n                        wvalue1++;\n                }\n            }\n        if (!wvalue2)\n            if (BN_is_bit_set(p2, b)) {\n                i = b - window2 + 1;\n                while (!BN_is_bit_set(p2, i))\n                    i++;\n                wpos2 = i;\n                wvalue2 = 1;\n                for (i = b - 1; i >= wpos2; i--) {\n                    wvalue2 <<= 1;\n                    if (BN_is_bit_set(p2, i))\n                        wvalue2++;\n                }\n            }\n        if (wvalue1 && b == wpos1) {\n            if (!BN_mod_mul_montgomery(r, r, val1[wvalue1 >> 1], mont, ctx))\n                goto err;\n            wvalue1 = 0;\n            r_is_one = 0;\n        }\n        if (wvalue2 && b == wpos2) {\n            if (!BN_mod_mul_montgomery(r, r, val2[wvalue2 >> 1], mont, ctx))\n                goto err;\n            wvalue2 = 0;\n            r_is_one = 0;\n        }\n    }\n    if (!BN_from_montgomery(rr, r, mont, ctx))\n        goto err;\n    ret = 1;\n err:\n    if (in_mont == NULL)\n        BN_MONT_CTX_free(mont);\n    BN_CTX_end(ctx);\n    bn_check_top(rr);\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}', 'BIGNUM *BN_CTX_get(BN_CTX *ctx)\n{\n    BIGNUM *ret;\n    CTXDBG("ENTER BN_CTX_get()", ctx);\n    if (ctx->err_stack || ctx->too_many)\n        return NULL;\n    if ((ret = BN_POOL_get(&ctx->pool, ctx->flags)) == NULL) {\n        ctx->too_many = 1;\n        BNerr(BN_F_BN_CTX_GET, BN_R_TOO_MANY_TEMPORARY_VARIABLES);\n        return NULL;\n    }\n    BN_zero(ret);\n    ret->flags &= (~BN_FLG_CONSTTIME);\n    ctx->used++;\n    CTXDBG("LEAVE BN_CTX_get()", ctx);\n    return ret;\n}', 'int BN_to_montgomery(BIGNUM *r, const BIGNUM *a, BN_MONT_CTX *mont,\n                     BN_CTX *ctx)\n{\n    return BN_mod_mul_montgomery(r, a, &(mont->RR), mont, ctx);\n}', 'int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,\n                          BN_MONT_CTX *mont, BN_CTX *ctx)\n{\n    int ret = bn_mul_mont_fixed_top(r, a, b, mont, ctx);\n    bn_correct_top(r);\n    bn_check_top(r);\n    return ret;\n}', 'int bn_mul_mont_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,\n                          BN_MONT_CTX *mont, BN_CTX *ctx)\n{\n    BIGNUM *tmp;\n    int ret = 0;\n    int num = mont->N.top;\n#if defined(OPENSSL_BN_ASM_MONT) && defined(MONT_WORD)\n    if (num > 1 && a->top == num && b->top == num) {\n        if (bn_wexpand(r, num) == NULL)\n            return 0;\n        if (bn_mul_mont(r->d, a->d, b->d, mont->N.d, mont->n0, num)) {\n            r->neg = a->neg ^ b->neg;\n            r->top = num;\n            r->flags |= BN_FLG_FIXED_TOP;\n            return 1;\n        }\n    }\n#endif\n    if ((a->top + b->top) > 2 * num)\n        return 0;\n    BN_CTX_start(ctx);\n    tmp = BN_CTX_get(ctx);\n    if (tmp == NULL)\n        goto err;\n    bn_check_top(tmp);\n    if (a == b) {\n        if (!bn_sqr_fixed_top(tmp, a, ctx))\n            goto err;\n    } else {\n        if (!bn_mul_fixed_top(tmp, a, b, ctx))\n            goto err;\n    }\n#ifdef MONT_WORD\n    if (!bn_from_montgomery_word(r, tmp, mont))\n        goto err;\n#else\n    if (!BN_from_montgomery(r, tmp, mont, ctx))\n        goto err;\n#endif\n    ret = 1;\n err:\n    BN_CTX_end(ctx);\n    return ret;\n}', 'int bn_mul_fixed_top(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)\n{\n    int ret = 0;\n    int top, al, bl;\n    BIGNUM *rr;\n#if defined(BN_MUL_COMBA) || defined(BN_RECURSION)\n    int i;\n#endif\n#ifdef BN_RECURSION\n    BIGNUM *t = NULL;\n    int j = 0, k;\n#endif\n    bn_check_top(a);\n    bn_check_top(b);\n    bn_check_top(r);\n    al = a->top;\n    bl = b->top;\n    if ((al == 0) || (bl == 0)) {\n        BN_zero(r);\n        return 1;\n    }\n    top = al + bl;\n    BN_CTX_start(ctx);\n    if ((r == a) || (r == b)) {\n        if ((rr = BN_CTX_get(ctx)) == NULL)\n            goto err;\n    } else\n        rr = r;\n#if defined(BN_MUL_COMBA) || defined(BN_RECURSION)\n    i = al - bl;\n#endif\n#ifdef BN_MUL_COMBA\n    if (i == 0) {\n# if 0\n        if (al == 4) {\n            if (bn_wexpand(rr, 8) == NULL)\n                goto err;\n            rr->top = 8;\n            bn_mul_comba4(rr->d, a->d, b->d);\n            goto end;\n        }\n# endif\n        if (al == 8) {\n            if (bn_wexpand(rr, 16) == NULL)\n                goto err;\n            rr->top = 16;\n            bn_mul_comba8(rr->d, a->d, b->d);\n            goto end;\n        }\n    }\n#endif\n#ifdef BN_RECURSION\n    if ((al >= BN_MULL_SIZE_NORMAL) && (bl >= BN_MULL_SIZE_NORMAL)) {\n        if (i >= -1 && i <= 1) {\n            if (i >= 0) {\n                j = BN_num_bits_word((BN_ULONG)al);\n            }\n            if (i == -1) {\n                j = BN_num_bits_word((BN_ULONG)bl);\n            }\n            j = 1 << (j - 1);\n            assert(j <= al || j <= bl);\n            k = j + j;\n            t = BN_CTX_get(ctx);\n            if (t == NULL)\n                goto err;\n            if (al > j || bl > j) {\n                if (bn_wexpand(t, k * 4) == NULL)\n                    goto err;\n                if (bn_wexpand(rr, k * 4) == NULL)\n                    goto err;\n                bn_mul_part_recursive(rr->d, a->d, b->d,\n                                      j, al - j, bl - j, t->d);\n            } else {\n                if (bn_wexpand(t, k * 2) == NULL)\n                    goto err;\n                if (bn_wexpand(rr, k * 2) == NULL)\n                    goto err;\n                bn_mul_recursive(rr->d, a->d, b->d, j, al - j, bl - j, t->d);\n            }\n            rr->top = top;\n            goto end;\n        }\n    }\n#endif\n    if (bn_wexpand(rr, top) == NULL)\n        goto err;\n    rr->top = top;\n    bn_mul_normal(rr->d, a->d, al, b->d, bl);\n#if defined(BN_MUL_COMBA) || defined(BN_RECURSION)\n end:\n#endif\n    rr->neg = a->neg ^ b->neg;\n    rr->flags |= BN_FLG_FIXED_TOP;\n    if (r != rr && BN_copy(r, rr) == NULL)\n        goto err;\n    ret = 1;\n err:\n    bn_check_top(r);\n    BN_CTX_end(ctx);\n    return ret;\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}']