ETB_FRAME_SIZE_WORDS
frame_off = write_ptr % ETB_FRAME_SIZE_WORDS;
frame_endoff = ETB_FRAME_SIZE_WORDS - frame_off;
capacity = drvdata->buffer_depth * ETB_FRAME_SIZE_WORDS;
if (write_ptr % ETB_FRAME_SIZE_WORDS) {
write_ptr &= ~(ETB_FRAME_SIZE_WORDS - 1);
to_read *= ETB_FRAME_SIZE_WORDS;
u32 mask = ~(ETB_FRAME_SIZE_WORDS - 1);
to_read / ETB_FRAME_SIZE_WORDS;