请问F28377里这两个函数的第一个参数是什么意思啊？

//Set the peripheral muxing for the specified pin. The appropriate
//parameters can be found in the GPIO Muxed Pins table(4.4) in the datasheet.
//Use the GPIO index row (0 to 15) to select a muxing option for the GPIO.

void GPIO_SetupPinMux(Uint16 pin, Uint16 cpu, Uint16 peripheral)

//Setup up the GPIO input/output options for the specified pin.
//The flags are a 16-bit mask produced by ORing together options.
//For input pins, the valid flags are:
//GPIO_PULLUP Enable pull-up
//GPIO_INVERT Enable input polarity inversion
//GPIO_SYNC Synchronize the input latch to PLLSYSCLK (default -- you don't need to specify this)
//GPIO_QUAL3 Use 3-sample qualification
//GPIO_QUAL6 Use 6-sample qualification
//GPIO_ASYNC Do not use synchronization or qualification
//(Note: only one of SYNC, QUAL3, QUAL6, or ASYNC is allowed)
//
//For output pins, the valid flags are:
//GPIO_OPENDRAIN Output in open drain mode
//GPIO_PULLUP If open drain enabled, also enable the pull-up
//and the input qualification flags (SYNC/QUAL3/QUAL6/SYNC) listed above.
//
//With no flags, the default input state is synchronous with no
//pull-up or polarity inversion. The default output state is
//the standard digital output.

void GPIO_SetupPinOptions(Uint16 pin, Uint16 output, Uint16 flags)

其实我就是这些注释话没看懂，后面两个参数我懂，就是第一个参数是怎么对应到GPIO上的？