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I would like to to use the bit addressable memory range (bdata) with an index variable as in the following example:
#define SETBIT(I) WAIT_4_MUTEX; flags^I=1; FREE_MUTEX; unsigned char bdata flags; func () { unsigned char i; for (i=0; i < MAX_CELL; i++) { // do interesting stuff SETBIT(i); } }
This construction of coarse gives a lval error on the use of the SETBIT macro.
My current fall back are the macro's:
#define SETBIT(I) base |= ((unsigned char) (1 << I)) #define CLEARBIT(I) base &= ~((unsigned char) (1 << I))
But still have the feeling that I am wasting cycles on the shift operators in these two macro's and because this is within a mutex region the timing might become an issue.
Is there a better way to set/reset the i-th bit of a bit addressable variable ?
Well, there is a suggestion, here is the listing for setting the second bit of the Hs_st1 bitfield:
C:0x2D4F 122FB9 LCALL OS_WAIT(C:2FB9) C:0x2D52 432202 ORL Hs_st1(0x22),#0x02 C:0x2D55 7F09 MOV R7,#0x09 C:0x2D57 123A72 LCALL OS_SEND_TOKEN(C:3A72)
The shifts apparently have been taken care of outside the critical region, probably even in the preproc's macro expansion. Although for that, in hindsight slightly embarrassing reason, this is what I wanted.
Thanks everybody for the contributions,
"In peace my mind withdraws"