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void emac_hal_lowlevel_init(emac_hal_context_t *hal);

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#if CONFIG_ETH_RMII_CLK_INPUT
#if CONFIG_ETH_RMII_CLK_IN_GPIO == 0
    /* RMII clock (50MHz) input to GPIO0 */
    PIN_FUNC_SELECT(PERIPHS_IO_MUX_GPIO0_U, FUNC_GPIO0_EMAC_TX_CLK);
    PIN_INPUT_ENABLE(GPIO_PIN_MUX_REG[0]);
#else
#error "ESP32 EMAC only support input RMII clock to GPIO0"
#endif
#endif
#if CONFIG_ETH_RMII_CLK_OUTPUT
#if CONFIG_ETH_RMII_CLK_OUTPUT_GPIO0
    /* APLL clock output to GPIO0 (must be configured to 50MHz!) */
    PIN_FUNC_SELECT(PERIPHS_IO_MUX_GPIO0_U, FUNC_GPIO0_CLK_OUT1);
    PIN_INPUT_DISABLE(GPIO_PIN_MUX_REG[0]);
#elif CONFIG_ETH_RMII_CLK_OUT_GPIO == 16
    /* RMII CLK (50MHz) output to GPIO16 */
    PIN_FUNC_SELECT(PERIPHS_IO_MUX_GPIO16_U, FUNC_GPIO16_EMAC_CLK_OUT);
    PIN_INPUT_DISABLE(GPIO_PIN_MUX_REG[16]);
#elif CONFIG_ETH_RMII_CLK_OUT_GPIO == 17
    /* RMII CLK (50MHz) output to GPIO17 */
    PIN_FUNC_SELECT(PERIPHS_IO_MUX_GPIO17_U, FUNC_GPIO17_EMAC_CLK_OUT_180);
    PIN_INPUT_DISABLE(GPIO_PIN_MUX_REG[17]);
#endif
#endif // CONFIG_ETH_RMII_CLK_OUTPUT
    /* Clock configuration */
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