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simplify _ff_correct_read_index()

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hathach
2023-01-07 18:50:19 +07:00
parent 248025bb6c
commit c29b7643a5
1 changed files with 77 additions and 60 deletions
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137
src/common/tusb_fifo.c
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@@ -314,51 +314,9 @@ static void _ff_pull_n(tu_fifo_t* f, void* app_buf, uint16_t n, uint16_t rel, tu
}
//--------------------------------------------------------------------+
// Index (free-running and real buffer pointer)
// Helper
//--------------------------------------------------------------------+
// Advance an absolute index
// "absolute" index is only in the range of [0..2*depth)
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 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*depth-1));
new_idx = (uint16_t) (new_idx + non_used_index_space);
}
return new_idx;
}
// 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_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*depth-1));
new_idx = (uint16_t) (new_idx - non_used_index_space);
}
return new_idx;
}
// index to pointer, simply an modulo with minus.
TU_ATTR_ALWAYS_INLINE static inline
uint16_t idx2ptr(uint16_t depth, uint16_t idx)
{
// Only run at most 3 times since index is limit in the range of [0..2*depth)
while ( idx >= depth ) idx -= depth;
return idx;
}
// return only the index difference and as such can be used to determine an overflow i.e overflowable count
TU_ATTR_ALWAYS_INLINE static inline
uint16_t _ff_count(uint16_t depth, uint16_t wr_idx, uint16_t rd_idx)
@@ -392,12 +350,72 @@ uint16_t _ff_remaining(uint16_t depth, uint16_t wr_idx, uint16_t rd_idx)
return (depth > count) ? (depth - count) : 0;
}
// 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 wr_idx)
//--------------------------------------------------------------------+
// Index Helper
//--------------------------------------------------------------------+
// Advance an absolute index
// "absolute" index is only in the range of [0..2*depth)
static uint16_t advance_index(uint16_t depth, uint16_t idx, uint16_t offset)
{
f->rd_idx = backward_index(f->depth, wr_idx, f->depth);
// 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_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*depth-1));
new_idx = (uint16_t) (new_idx + non_used_index_space);
}
return new_idx;
}
#if 0 // not used but
// 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_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*depth-1));
new_idx = (uint16_t) (new_idx - non_used_index_space);
}
return new_idx;
}
#endif
// index to pointer, simply an modulo with minus.
TU_ATTR_ALWAYS_INLINE static inline
uint16_t idx2ptr(uint16_t depth, uint16_t idx)
{
// Only run at most 3 times since index is limit in the range of [0..2*depth)
while ( idx >= depth ) idx -= depth;
return idx;
}
// Works on local copies of w
// When an overwritable fifo is overflowed, rd_idx will be re-index so that it forms
// an full fifo i.e _ff_count() = depth
TU_ATTR_ALWAYS_INLINE static inline
uint16_t _ff_correct_read_index(tu_fifo_t* f, uint16_t wr_idx)
{
uint16_t rd_idx;
if ( wr_idx >= f->depth )
{
rd_idx = wr_idx - f->depth;
}else
{
rd_idx = wr_idx + f->depth;
}
f->rd_idx = rd_idx;
return rd_idx;
}
// Works on local copies of w and r
@@ -407,14 +425,14 @@ static bool _tu_fifo_peek(tu_fifo_t* f, void * p_buffer, uint16_t wr_idx, uint16
uint16_t cnt = _ff_count(f->depth, wr_idx, rd_idx);
// Check overflow and correct if required
if (cnt > f->depth)
if ( cnt > f->depth )
{
_tu_fifo_correct_read_pointer(f, wr_idx);
rd_idx = _ff_correct_read_index(f, wr_idx);
cnt = f->depth;
}
// Skip beginning of buffer
if (cnt == 0) return false;
if ( cnt == 0 ) return false;
uint16_t rd_ptr = idx2ptr(f->depth, rd_idx);
@@ -431,18 +449,17 @@ static uint16_t _tu_fifo_peek_n(tu_fifo_t* f, void * p_buffer, uint16_t n, uint1
uint16_t cnt = _ff_count(f->depth, wr_idx, rd_idx);
// Check overflow and correct if required
if (cnt > f->depth)
if ( cnt > f->depth )
{
_tu_fifo_correct_read_pointer(f, wr_idx);
rd_idx = f->rd_idx;
rd_idx = _ff_correct_read_index(f, wr_idx);
cnt = f->depth;
}
// Skip beginning of buffer
if (cnt == 0) return 0;
if ( cnt == 0 ) return 0;
// Check if we can read something at and after offset - if too less is available we read what remains
if (cnt < n) n = cnt;
if ( cnt < n ) n = cnt;
uint16_t rd_ptr = idx2ptr(f->depth, rd_idx);
@@ -662,7 +679,7 @@ bool tu_fifo_overflowed(tu_fifo_t* f)
void tu_fifo_correct_read_pointer(tu_fifo_t* f)
{
_ff_lock(f->mutex_rd);
_tu_fifo_correct_read_pointer(f, f->wr_idx);
_ff_correct_read_index(f, f->wr_idx);
_ff_unlock(f->mutex_rd);
}
@@ -963,10 +980,9 @@ void tu_fifo_get_read_info(tu_fifo_t *f, tu_fifo_buffer_info_t *info)
if (cnt > f->depth)
{
_ff_lock(f->mutex_rd);
_tu_fifo_correct_read_pointer(f, wr_idx);
rd_idx = _ff_correct_read_index(f, wr_idx);
_ff_unlock(f->mutex_rd);
rd_idx = f->rd_idx;
cnt = f->depth;
}
@@ -988,7 +1004,8 @@ void tu_fifo_get_read_info(tu_fifo_t *f, tu_fifo_buffer_info_t *info)
info->ptr_lin = &f->buffer[rd_ptr];
// Check if there is a wrap around necessary
if (wr_ptr > rd_ptr) {
if (wr_ptr > rd_ptr)
{
// Non wrapping case
info->len_lin = cnt;