RCC_OscInitTypeDef *oscSelector;
RCC_ClkInitTypeDef *clkSelector;

clkSelector->SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
clkSelector->ClockType = RCC_CLOCKTYPE_SYSCLK;
...
oscSelector->OscillatorType = RCC_OSCILLATORTYPE_HSE;
oscSelector->HSEState = RCC_HSE_ON;
...

void systemClockInit()
{
    RCC_OscInitTypeDef *oscSel;
    RCC_ClkInitTypeDef *clk;
    GPIO_InitTypeDef *mco;
        
    oscSel->OscillatorType = RCC_OSCILLATORTYPE_HSE;
    oscSel->HSEState = RCC_HSE_ON;
    oscSel->PLL.PLLSource = RCC_PLLSOURCE_HSE;
    oscSel->PLL.PLLState = RCC_PLL_ON;
    oscSel->PLL.PLLM = 8;
    oscSel->PLL.PLLN = 192;
    oscSel->PLL.PLLP = RCC_PLLP_DIV4;
    oscSel->PLL.PLLQ = 4;
    HAL_RCC_OscConfig(oscSel);
    
    clk->SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
    clk->ClockType = RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2;
    clk->AHBCLKDivider = RCC_SYSCLK_DIV1;
    clk->APB1CLKDivider = RCC_HCLK_DIV2;
    clk->APB2CLKDivider = RCC_HCLK_DIV2;
    HAL_RCC_ClockConfig(clk, FLASH_LATENCY_1);
    
    mco->Pin = GPIO_PIN_9;
    mco->Mode = GPIO_MODE_AF_PP;
    mco->Pull = GPIO_NOPULL;
    mco->Speed = GPIO_SPEED_HIGH;
    mco->Alternate = GPIO_AF0_MCO;
    HAL_GPIO_Init(GPIOC, mco);
    HAL_RCC_MCOConfig(RCC_MCO2, RCC_MCO2SOURCE_SYSCLK, RCC_MCODIV_1);
}

RCC_OscInitTypeDef oscSelector;
RCC_ClkInitTypeDef clkSelector;

&oscSelector;
&clkSelector;

RCC_OscInitTypeDef *oscSelector;