static unsigned int BN_STACK_pop(BN_STACK *st)
{
    return st->indexes[--(st->depth)];
}
['int ec_GF2m_simple_cmp(const EC_GROUP *group, const EC_POINT *a,\n                       const EC_POINT *b, BN_CTX *ctx)\n{\n    BIGNUM *aX, *aY, *bX, *bY;\n    BN_CTX *new_ctx = NULL;\n    int ret = -1;\n    if (EC_POINT_is_at_infinity(group, a)) {\n        return EC_POINT_is_at_infinity(group, b) ? 0 : 1;\n    }\n    if (EC_POINT_is_at_infinity(group, b))\n        return 1;\n    if (a->Z_is_one && b->Z_is_one) {\n        return ((BN_cmp(a->X, b->X) == 0) && BN_cmp(a->Y, b->Y) == 0) ? 0 : 1;\n    }\n    if (ctx == NULL) {\n        ctx = new_ctx = BN_CTX_new();\n        if (ctx == NULL)\n            return -1;\n    }\n    BN_CTX_start(ctx);\n    aX = BN_CTX_get(ctx);\n    aY = BN_CTX_get(ctx);\n    bX = BN_CTX_get(ctx);\n    bY = BN_CTX_get(ctx);\n    if (bY == NULL)\n        goto err;\n    if (!EC_POINT_get_affine_coordinates(group, a, aX, aY, ctx))\n        goto err;\n    if (!EC_POINT_get_affine_coordinates(group, b, bX, bY, ctx))\n        goto err;\n    ret = ((BN_cmp(aX, bX) == 0) && BN_cmp(aY, bY) == 0) ? 0 : 1;\n err:\n    BN_CTX_end(ctx);\n    BN_CTX_free(new_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}']