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util/fifo8: Allow fifo8_pop_buf() to not populate popped length

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There might be cases where we know the number of bytes we can
pop from the FIFO, or we simply don't care how many bytes is
returned. Allow fifo8_pop_buf() to take a NULL numptr.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Francisco Iglesias <frasse.iglesias@gmail.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20231109192814.95977-2-philmd@linaro.org>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
This commit is contained in:
Philippe Mathieu-Daudé 2023-11-09 20:28:05 +01:00 committed by Mark Cave-Ayland
parent 9468484fe9
commit cd04033dbe
2 changed files with 13 additions and 9 deletions
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10
include/qemu/fifo8.h
View File

@ -71,7 +71,7 @@ uint8_t fifo8_pop(Fifo8 *fifo);
* fifo8_pop_buf:
* @fifo: FIFO to pop from
* @max: maximum number of bytes to pop
* @num: actual number of returned bytes
* @numptr: pointer filled with number of bytes returned (can be NULL)
*
* Pop a number of elements from the FIFO up to a maximum of max. The buffer
* containing the popped data is returned. This buffer points directly into
@ -82,16 +82,16 @@ uint8_t fifo8_pop(Fifo8 *fifo);
* around in the ring buffer; in this case only a contiguous part of the data
* is returned.
*
* The number of valid bytes returned is populated in *num; will always return
* at least 1 byte. max must not be 0 or greater than the number of bytes in
* the FIFO.
* The number of valid bytes returned is populated in *numptr; will always
* return at least 1 byte. max must not be 0 or greater than the number of
* bytes in the FIFO.
*
* Clients are responsible for checking the availability of requested data
* using fifo8_num_used().
*
* Returns: A pointer to popped data.
*/
const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *num);
const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr);
/**
* fifo8_reset:

12
util/fifo8.c
View File

@ -66,16 +66,20 @@ uint8_t fifo8_pop(Fifo8 *fifo)
return ret;
}
const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *num)
const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *numptr)
{
uint8_t *ret;
uint32_t num;
assert(max > 0 && max <= fifo->num);
*num = MIN(fifo->capacity - fifo->head, max);
num = MIN(fifo->capacity - fifo->head, max);
ret = &fifo->data[fifo->head];
fifo->head += *num;
fifo->head += num;
fifo->head %= fifo->capacity;
fifo->num -= *num;
fifo->num -= num;
if (numptr) {
*numptr = num;
}
return ret;
}