Other Parts Discussed in Thread: MSP430F5438
Hello everyone,
i have a little question: i am using the msp430f5438 experiment board. There is a programm for testing issues preinstalled.
UserExpirience, some might know it, which explains all the functions of the MSP430, for example there are LEDs blinking, then there is a LCD attached, which can show a lot of things, like clock or little games.
Now my question is something code-specific, in the library of this project:
\MSP-EXP430F5438_User_Experience_16KB\F5XX_6XX_Core_Lib\hal_macros.h
there is this macro:
/*
* This macro is for use by other macros to form a fully valid C statement.
*/
#define st(x) do { x } while (__LINE__ == -1)
and i do not understand what the while-statement is about, i already know that __LINE__ will give out the current program-line, but how can this ever be "-1"?
And i know what the whole define statement does, so this is not my problem.
I assume this is some standart C-command, so i hope some of you can easily explain it to me.
Later in the programm this macro is used like this:
/*************************************************************************
* MACROS
**************************************************************************/
/* Select source for FLLREF e.g. SELECT_FLLREF(SELREF__XT1CLK) */
#define SELECT_FLLREF(source) st(UCSCTL3 = (UCSCTL3 & ~(SELREF_7)) | (source);)
/* Select source for ACLK e.g. SELECT_ACLK(SELA__XT1CLK) */
#define SELECT_ACLK(source) st(UCSCTL4 = (UCSCTL4 & ~(SELA_7)) | (source);)
/* Select source for MCLK e.g. SELECT_MCLK(SELM__XT2CLK) */
#define SELECT_MCLK(source) st(UCSCTL4 = (UCSCTL4 & ~(SELM_7)) | (source);)
I guess it is just some kind of check, if the statement can be true at all or something.
Thanks for youre time and effort.
Greetings, Seb.
