PSR_C
frame->tf_spsr &= ~PSR_C; /* carry bit */
frame->tf_spsr |= PSR_C; /* carry bit */
frame->tf_spsr &= ~PSR_C; /* carry bit */
frame->tf_spsr &= ~PSR_C; /* carry bit */
frame->tf_spsr |= PSR_C; /* carry bit */
frame->tf_spsr &= ~PSR_C; /* carry bit */
tf->tf_epsr &= ~PSR_C;
tf->tf_epsr |= PSR_C; /* fail */
tf->tf_epsr &= ~PSR_C;
tf->tf_epsr |= PSR_C; /* fail */
tf->tf_epsr &= ~PSR_C;