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Merge pull request #940 from HiFiPhile/fifo_fix

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Fix fifo overflow correction.
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Ha Thach 2021-07-01 02:25:23 +07:00 committed by GitHub
commit 9b3ec69b27
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2 changed files with 26 additions and 2 deletions
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4
src/common/tusb_fifo.c
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@ -325,7 +325,7 @@ static uint16_t advance_pointer(tu_fifo_t* f, uint16_t p, uint16_t offset)
// We are exploiting the wrap around to the correct index // We are exploiting the wrap around to the correct index
// TODO warning: assuming signed overflow does not occur when assuming that (X + c) < X is always false [-Wstrict-overflow] // TODO warning: assuming signed overflow does not occur when assuming that (X + c) < X is always false [-Wstrict-overflow]
if ((p > p + offset) || (p + offset > f->max_pointer_idx)) if ((p > (uint16_t)(p + offset)) || ((uint16_t)(p + offset) > f->max_pointer_idx))
{ {
p = (p + offset) + f->non_used_index_space; p = (p + offset) + f->non_used_index_space;
} }
@ -342,7 +342,7 @@ static uint16_t backward_pointer(tu_fifo_t* f, uint16_t p, uint16_t offset)
// We limit the index space of p such that a correct wrap around happens // 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!! // 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 // We are exploiting the wrap around to the correct index
if ((p < p - offset) || (p - offset > f->max_pointer_idx)) if ((p < (uint16_t)(p - offset)) || ((uint16_t)(p - offset) > f->max_pointer_idx))
{ {
p = (p - offset) - f->non_used_index_space; p = (p - offset) - f->non_used_index_space;
} }

24
test/test/test_fifo.c
View File

@ -292,3 +292,27 @@ void test_full(void)
// write info // write info
} }
void test_rd_idx_wrap()
{
tu_fifo_t ff10;
uint8_t buf[10];
uint8_t dst[10];
tu_fifo_config(&ff10, buf, 10, 1, 1);
uint16_t n;
ff10.wr_idx = 6;
ff10.rd_idx = 15;
n = tu_fifo_read_n(&ff10, dst, 4);
TEST_ASSERT_EQUAL(n, 4);
TEST_ASSERT_EQUAL(ff10.rd_idx, 0);
n = tu_fifo_read_n(&ff10, dst, 4);
TEST_ASSERT_EQUAL(n, 4);
TEST_ASSERT_EQUAL(ff10.rd_idx, 4);
n = tu_fifo_read_n(&ff10, dst, 4);
TEST_ASSERT_EQUAL(n, 2);
TEST_ASSERT_EQUAL(ff10.rd_idx, 6);
}