diff --git a/src/common/tusb_fifo.c b/src/common/tusb_fifo.c index cdb0df73f..8de58c4a4 100644 --- a/src/common/tusb_fifo.c +++ b/src/common/tusb_fifo.c @@ -319,35 +319,35 @@ static void _ff_pull_n(tu_fifo_t* f, void* app_buf, uint16_t n, uint16_t rel, tu // Advance an absolute index // "absolute" index is only in the range of [0..2*depth) -static uint16_t advance_pointer(tu_fifo_t* f, uint16_t idx, uint16_t offset) +static uint16_t advance_index(uint16_t depth, uint16_t idx, uint16_t offset) { // We limit the index space of p such that a correct wrap around happens // Check for a wrap around or if we are in unused index space - This has to be checked first!! // We are exploiting the wrap around to the correct index - uint16_t next_p = (uint16_t) (idx + offset); - if ( (idx > next_p) || (next_p >= 2*f->depth) ) + uint16_t new_idx = (uint16_t) (idx + offset); + if ( (idx > new_idx) || (new_idx >= 2*depth) ) { - uint16_t const non_used_index_space = (uint16_t) (UINT16_MAX - (2*f->depth-1)); - next_p = (uint16_t) (next_p + non_used_index_space); + uint16_t const non_used_index_space = (uint16_t) (UINT16_MAX - (2*depth-1)); + new_idx = (uint16_t) (new_idx + non_used_index_space); } - return next_p; + return new_idx; } -// Backward an absolute pointer -static uint16_t backward_pointer(tu_fifo_t* f, uint16_t p, uint16_t offset) +// Backward an absolute index +static uint16_t backward_index(uint16_t depth, uint16_t idx, uint16_t offset) { // We limit the index space of p such that a correct wrap around happens // Check for a wrap around or if we are in unused index space - This has to be checked first!! // We are exploiting the wrap around to the correct index - uint16_t new_p = (uint16_t) (p - offset); - if ( (p < new_p) || (new_p >= 2*f->depth) ) + uint16_t new_idx = (uint16_t) (idx - offset); + if ( (idx < new_idx) || (new_idx >= 2*depth) ) { - uint16_t const non_used_index_space = (uint16_t) (UINT16_MAX - (2*f->depth-1)); - new_p = (uint16_t) (new_p - non_used_index_space); + uint16_t const non_used_index_space = (uint16_t) (UINT16_MAX - (2*depth-1)); + new_idx = (uint16_t) (new_idx - non_used_index_space); } - return new_p; + return new_idx; } // index to pointer, simply an modulo with minus. @@ -394,9 +394,9 @@ uint16_t _ff_remaining(uint16_t depth, uint16_t wr_idx, uint16_t rd_idx) // Works on local copies of w // For more details see _tu_fifo_overflow()! TU_ATTR_ALWAYS_INLINE static inline -void _tu_fifo_correct_read_pointer(tu_fifo_t* f, uint16_t wAbs) +void _tu_fifo_correct_read_pointer(tu_fifo_t* f, uint16_t wr_idx) { - f->rd_idx = backward_pointer(f, wAbs, f->depth); + f->rd_idx = backward_index(f->depth, wr_idx, f->depth); } // Works on local copies of w and r @@ -502,7 +502,7 @@ static uint16_t _tu_fifo_write_n(tu_fifo_t* f, const void * data, uint16_t n, tu // Double overflowed // Index is bigger than the allowed range [0,2*depth) // re-position write index to have a full fifo after pushed - wr_idx = advance_pointer(f, rd_idx, f->depth - n); + wr_idx = advance_index(f->depth, rd_idx, f->depth - n); // TODO we should also shift out n bytes from read index since we avoid changing rd index !! // However memmove() is expensive due to actual copying + wrapping consideration. @@ -528,7 +528,7 @@ static uint16_t _tu_fifo_write_n(tu_fifo_t* f, const void * data, uint16_t n, tu _ff_push_n(f, buf8, n, wr_ptr, copy_mode); // Advance index - f->wr_idx = advance_pointer(f, wr_idx, n); + f->wr_idx = advance_index(f->depth, wr_idx, n); TU_LOG(TU_FIFO_DBG, "\tnew_wr = %u\n", f->wr_idx); } @@ -547,7 +547,7 @@ static uint16_t _tu_fifo_read_n(tu_fifo_t* f, void * buffer, uint16_t n, tu_fifo n = _tu_fifo_peek_n(f, buffer, n, f->wr_idx, f->rd_idx, copy_mode); // Advance read pointer - f->rd_idx = advance_pointer(f, f->rd_idx, n); + f->rd_idx = advance_index(f->depth, f->rd_idx, n); _ff_unlock(f->mutex_rd); return n; @@ -690,7 +690,7 @@ bool tu_fifo_read(tu_fifo_t* f, void * buffer) bool ret = _tu_fifo_peek(f, buffer, f->wr_idx, f->rd_idx); // Advance pointer - f->rd_idx = advance_pointer(f, f->rd_idx, ret); + f->rd_idx = advance_index(f->depth, f->rd_idx, ret); _ff_unlock(f->mutex_rd); return ret; @@ -800,7 +800,7 @@ bool tu_fifo_write(tu_fifo_t* f, const void * data) _ff_push(f, data, wr_ptr); // Advance pointer - f->wr_idx = advance_pointer(f, wr_idx, 1); + f->wr_idx = advance_index(f->depth, wr_idx, 1); ret = true; } @@ -911,7 +911,7 @@ bool tu_fifo_set_overwritable(tu_fifo_t *f, bool overwritable) /******************************************************************************/ void tu_fifo_advance_write_pointer(tu_fifo_t *f, uint16_t n) { - f->wr_idx = advance_pointer(f, f->wr_idx, n); + f->wr_idx = advance_index(f->depth, f->wr_idx, n); } /******************************************************************************/ @@ -932,7 +932,7 @@ void tu_fifo_advance_write_pointer(tu_fifo_t *f, uint16_t n) /******************************************************************************/ void tu_fifo_advance_read_pointer(tu_fifo_t *f, uint16_t n) { - f->rd_idx = advance_pointer(f, f->rd_idx, n); + f->rd_idx = advance_index(f->depth, f->rd_idx, n); } /******************************************************************************/