On Fri, Mar 07, 2003 at 11:35:02AM -0500, Mark Stokes wrote: > I have a macro: > #define SPITXWAIT while ( !( IFG1 & UTXIFG0 ) ); // Wait for the TX > That is expanding to this: > > SPITXWAIT; // USART0 TX buffer ready? > 1994: c2 93 02 00 cmp.b #0, &0x0002 > 1998: fd 37 jge $-4 ;abs dst addr > 0x1994 > > Even though this is seeminging to work, why is UTXIFG0 being expanded to > "#0" instead of "0x80" as it should be. Here is the macro definitions > in the header file: > #define UTXIFG0 (1<<7)
It is working because anything greater or equal 0x0 has bit 7 clear, if something is less than 0, it will have bit 7 set. Maybe it is an optimization feature, or something... > Try as I might, I cannot get the cmp.b to compare w/ 0x80. It seems > stuck on only comparing Zero with IFG1. This also happens when I use > something else, like U0TCTL. Or if I use this macro definition: > #define SPITXWAIT while ( !( IFG1 & 0x80 ) ); // Wait for the TX > > Any ideas? Maybe you should try to define everything with a cast to (unsigned char). Try to define UTXIFG0 as: #define UTXIFG0 ((unsigned char) 1<<7) And IFG1 in the same way.
