Custom_FIFO 是在 user_define.h 中定义的结构。图 2-5 中也显示了 CUSTOM_FIFO。

typedef struct {
    uint16_t fifo_in;
    uint16_t fifo_out;
    uint16_t fifo_count;
    Custom_Element *fifo_pointer;
} Custom_FIFO;

gCan2I2c_FIFO 和 gI2c2Can_FIFO 在 main.c 中定义。请注意 SRAM 的使用量，它与 C2I_FIFO_SIZE、ItoC_FIFO_SIZE 以及 Custom_Element 的大小有关。

/* Variables for ItoC_FIFO
 * ItoC_FIFO is used to temporarily store message from I2C to CAN */
Custom_Element gItoC_FIFO[ItoC_FIFO_SIZE];
Custom_FIFO gI2c2Can_FIFO = {0, 0, 0, gItoC_FIFO};

/* Variables for C2I_FIFO
 * C2I_FIFO is used to temporarily store message from CAN to I2C */
Custom_Element gC2I_FIFO[C2I_FIFO_SIZE];
Custom_FIFO gCan2I2c_FIFO = {0, 0, 0, gC2I_FIFO};