FRAME_SIZE
for (i = 0; i < FRAME_SIZE; i++)
memset(tfp->tf_regs, 0, FRAME_SIZE * sizeof tfp->tf_regs[0]);
unsigned long tf_regs[FRAME_SIZE]; /* See above */
lda sp, FRAME_SIZE(sp)
lda sp, -FRAME_SIZE(sp)
while (off > FRAME_SIZE + 2) {