From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46998) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WCAIH-00077q-0M for qemu-devel@nongnu.org; Sat, 08 Feb 2014 10:58:14 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WCAIF-0002se-Pa for qemu-devel@nongnu.org; Sat, 08 Feb 2014 10:58:12 -0500 Received: from mnementh.archaic.org.uk ([2001:8b0:1d0::1]:45683) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WCAIF-0002sW-GJ for qemu-devel@nongnu.org; Sat, 08 Feb 2014 10:58:11 -0500 From: Peter Maydell Date: Sat, 8 Feb 2014 15:58:00 +0000 Message-Id: <1391875084-12772-26-git-send-email-peter.maydell@linaro.org> In-Reply-To: <1391875084-12772-1-git-send-email-peter.maydell@linaro.org> References: <1391875084-12772-1-git-send-email-peter.maydell@linaro.org> Subject: [Qemu-devel] [PULL 25/29] util/fifo8: implement push/pop of multiple bytes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Blue Swirl , qemu-devel@nongnu.org, Aurelien Jarno From: Beniamino Galvani The patch adds functions fifo8_push_all() and fifo8_pop_buf() which can be used respectively to push the content of a memory buffer to the fifo and to pop multiple bytes obtaining a pointer to the fifo backing buffer. In addition, it implements fifo8_num_free() and fifo8_num_used() which allow to check if a multi-byte operation can be performed. Signed-off-by: Beniamino Galvani Reviewed-by: Peter Crosthwaite Signed-off-by: Peter Maydell --- include/qemu/fifo8.h | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++ util/fifo8.c | 46 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 107 insertions(+) diff --git a/include/qemu/fifo8.h b/include/qemu/fifo8.h index d318f71..8820780 100644 --- a/include/qemu/fifo8.h +++ b/include/qemu/fifo8.h @@ -44,6 +44,19 @@ void fifo8_destroy(Fifo8 *fifo); void fifo8_push(Fifo8 *fifo, uint8_t data); /** + * fifo8_push_all: + * @fifo: FIFO to push to + * @data: data to push + * @size: number of bytes to push + * + * Push a byte array to the FIFO. Behaviour is undefined if the FIFO is full. + * Clients are responsible for checking the space left in the FIFO using + * fifo8_num_free(). + */ + +void fifo8_push_all(Fifo8 *fifo, const uint8_t *data, uint32_t num); + +/** * fifo8_pop: * @fifo: fifo to pop from * @@ -56,6 +69,32 @@ void fifo8_push(Fifo8 *fifo, uint8_t data); 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 + * + * 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 + * the FIFO backing store and data is invalidated once any of the fifo8_* APIs + * are called on the FIFO. + * + * The function may return fewer bytes than requested when the data wraps + * 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. + * + * 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); + +/** * fifo8_reset: * @fifo: FIFO to reset * @@ -86,6 +125,28 @@ bool fifo8_is_empty(Fifo8 *fifo); bool fifo8_is_full(Fifo8 *fifo); +/** + * fifo8_num_free: + * @fifo: FIFO to check + * + * Return the number of free bytes in the FIFO. + * + * Returns: Number of free bytes. + */ + +uint32_t fifo8_num_free(Fifo8 *fifo); + +/** + * fifo8_num_used: + * @fifo: FIFO to check + * + * Return the number of used bytes in the FIFO. + * + * Returns: Number of used bytes. + */ + +uint32_t fifo8_num_used(Fifo8 *fifo); + extern const VMStateDescription vmstate_fifo8; #define VMSTATE_FIFO8(_field, _state) { \ diff --git a/util/fifo8.c b/util/fifo8.c index 013e903..a7503c2 100644 --- a/util/fifo8.c +++ b/util/fifo8.c @@ -37,6 +37,27 @@ void fifo8_push(Fifo8 *fifo, uint8_t data) fifo->num++; } +void fifo8_push_all(Fifo8 *fifo, const uint8_t *data, uint32_t num) +{ + uint32_t start, avail; + + if (fifo->num + num > fifo->capacity) { + abort(); + } + + start = (fifo->head + fifo->num) % fifo->capacity; + + if (start + num <= fifo->capacity) { + memcpy(&fifo->data[start], data, num); + } else { + avail = fifo->capacity - start; + memcpy(&fifo->data[start], data, avail); + memcpy(&fifo->data[0], &data[avail], num - avail); + } + + fifo->num += num; +} + uint8_t fifo8_pop(Fifo8 *fifo) { uint8_t ret; @@ -50,6 +71,21 @@ uint8_t fifo8_pop(Fifo8 *fifo) return ret; } +const uint8_t *fifo8_pop_buf(Fifo8 *fifo, uint32_t max, uint32_t *num) +{ + uint8_t *ret; + + if (max == 0 || max > fifo->num) { + abort(); + } + *num = MIN(fifo->capacity - fifo->head, max); + ret = &fifo->data[fifo->head]; + fifo->head += *num; + fifo->head %= fifo->capacity; + fifo->num -= *num; + return ret; +} + void fifo8_reset(Fifo8 *fifo) { fifo->num = 0; @@ -65,6 +101,16 @@ bool fifo8_is_full(Fifo8 *fifo) return (fifo->num == fifo->capacity); } +uint32_t fifo8_num_free(Fifo8 *fifo) +{ + return fifo->capacity - fifo->num; +} + +uint32_t fifo8_num_used(Fifo8 *fifo) +{ + return fifo->num; +} + const VMStateDescription vmstate_fifo8 = { .name = "Fifo8", .version_id = 1, -- 1.8.5