------- Comment #11 from anrp at mit dot edu 2007-09-08 21:48 ------- (In reply to comment #10) > Here's an untested (I'm going to try to figure out how to get it to build into > the AVR build) function that replaces the definition of clz_tab with a 6 > instruction bit of code: > > ; r2 in, r3 out > ; r2 clobbered > ; Z, C, N. V clobbered > clz_compute: > ldi r3, 0x09 ; preload output > clc ; clear C (guarentees termination with 8 loops) > clz_compute_loop1: > rol r2 ; push MSB into C > dec r3 ; dec output > brcs clz_end ; if C is set (msb was set), we're done > rjmp clz_compute_loop1 ; otherwise, repeat > clz_end: >
And the first bug of the day, clc should be sec. brcs will only jump out if C is set. On to prodding gcc... -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29524
