From b40ace72dd1b940fc0ce6e4a5e06346439dd5625 Mon Sep 17 00:00:00 2001
From: Josh Blum <josh@joshknows.com>
Date: Wed, 6 Oct 2010 18:41:30 -0700
Subject: usrp1: use the transport frame sizes to calculate the max spp
The max send spp is the frame size minus the alignment padding.
This allows us to copy a remainder into a new buffer and always
commit multiples of the alignment size (512 bytes).
Reworked the managed send buffer implementation to handle the above.
Uses only managed memory, and only mem-copied under the alignment.
---
host/lib/usrp/usrp1/io_impl.cpp | 169 +++++++++++++++++++++----------------
host/lib/usrp/usrp1/usrp1_impl.hpp | 10 +--
2 files changed, 99 insertions(+), 80 deletions(-)
(limited to 'host/lib/usrp')
diff --git a/host/lib/usrp/usrp1/io_impl.cpp b/host/lib/usrp/usrp1/io_impl.cpp
index 676b1536a..0a16f7a43 100644
--- a/host/lib/usrp/usrp1/io_impl.cpp
+++ b/host/lib/usrp/usrp1/io_impl.cpp
@@ -33,6 +33,28 @@ using namespace uhd::usrp;
using namespace uhd::transport;
namespace asio = boost::asio;
+static const size_t alignment_padding = 512;
+
+/***********************************************************************
+ * Helper struct to associate an offset with a buffer
+ **********************************************************************/
+class offset_send_buffer{
+public:
+ typedef boost::shared_ptr<offset_send_buffer> sptr;
+
+ static sptr make(managed_send_buffer::sptr buff, size_t offset = 0){
+ return sptr(new offset_send_buffer(buff, offset));
+ }
+
+ //member variables
+ managed_send_buffer::sptr buff;
+ size_t offset; /* in bytes */
+
+private:
+ offset_send_buffer(managed_send_buffer::sptr buff, size_t offset):
+ buff(buff), offset(offset){/* NOP */}
+};
+
/***********************************************************************
* IO Implementation Details
**********************************************************************/
@@ -41,8 +63,7 @@ struct usrp1_impl::io_impl{
data_transport(data_transport),
underflow_poll_samp_count(0),
overflow_poll_samp_count(0),
- send_buff(data_transport->get_send_buff()),
- num_bytes_committed(0)
+ curr_buff(offset_send_buffer::make(data_transport->get_send_buff()))
{
/* NOP */
}
@@ -62,98 +83,88 @@ struct usrp1_impl::io_impl{
size_t overflow_poll_samp_count;
//wrapper around the actual send buffer interface
- //all of this to ensure only full buffers are committed
- managed_send_buffer::sptr send_buff;
- size_t num_bytes_committed;
- double send_timeout;
- boost::uint8_t pseudo_buff[BYTES_PER_PACKET];
- void phony_commit_pseudo_buff(size_t num_bytes);
- void phony_commit_send_buff(size_t num_bytes);
- void commit_send_buff(void);
+ //all of this to ensure only aligned lengths are committed
+ //NOTE: you must commit before getting a new buffer
+ //since the vrt packet handler obeys this, we are ok
+ offset_send_buffer::sptr curr_buff;
+ void commit_send_buff(offset_send_buffer::sptr, offset_send_buffer::sptr, size_t);
void flush_send_buff(void);
bool get_send_buffs(vrt_packet_handler::managed_send_buffs_t &, double);
-
- //helpers to get at the send buffer + offset
- inline void *get_send_mem_ptr(void){
- return send_buff->cast<boost::uint8_t *>() + num_bytes_committed;
- }
- inline size_t get_send_mem_size(void){
- return send_buff->size() - num_bytes_committed;
- }
};
/*!
- * Accept a commit of num bytes to the pseudo buffer.
- * Memcpy the entire contents of pseudo buffer into send buffers.
- *
- * Under most conditions:
- * The first loop iteration will fill the remainder of the send buffer.
- * The second loop iteration will empty the pseudo buffer remainder.
+ * Perform an actual commit on the send buffer:
+ * Copy the remainder of alignment to the next buffer.
+ * Commit the current buffer at multiples of alignment.
*/
-void usrp1_impl::io_impl::phony_commit_pseudo_buff(size_t num_bytes){
- size_t bytes_to_copy = num_bytes, bytes_copied = 0;
- while(bytes_to_copy){
- size_t bytes_copied_here = std::min(bytes_to_copy, get_send_mem_size());
- std::memcpy(get_send_mem_ptr(), pseudo_buff + bytes_copied, bytes_copied_here);
- phony_commit_send_buff(bytes_copied_here);
- bytes_to_copy -= bytes_copied_here;
- bytes_copied += bytes_copied_here;
- }
-}
+void usrp1_impl::io_impl::commit_send_buff(
+ offset_send_buffer::sptr curr,
+ offset_send_buffer::sptr next,
+ size_t num_bytes
+){
+ //total number of bytes now in the current buffer
+ size_t bytes_in_curr_buffer = curr->offset + num_bytes;
-/*!
- * Accept a commit of num bytes to the send buffer.
- * Conditionally commit the send buffer if full.
- */
-void usrp1_impl::io_impl::phony_commit_send_buff(size_t num_bytes){
- num_bytes_committed += num_bytes;
- if (num_bytes_committed != send_buff->size()) return;
- commit_send_buff();
+ //calculate how many to commit and remainder
+ size_t num_bytes_remaining = bytes_in_curr_buffer % alignment_padding;
+ size_t num_bytes_to_commit = bytes_in_curr_buffer - num_bytes_remaining;
+
+ //copy the remainder into the next buffer
+ std::memcpy(
+ next->buff->cast<char *>() + next->offset,
+ curr->buff->cast<char *>() + num_bytes_to_commit,
+ num_bytes_remaining
+ );
+
+ //update the offset into the next buffer
+ next->offset += num_bytes_remaining;
+
+ //commit the current buffer
+ curr->buff->commit(num_bytes_to_commit);
}
/*!
- * Flush the send buffer:
- * Zero-pad the send buffer to the nearest 512 byte boundary and commit.
+ * Flush the current buffer by padding out to alignment and committing.
*/
void usrp1_impl::io_impl::flush_send_buff(void){
- size_t bytes_to_pad = (-1*num_bytes_committed)%512;
- std::memset(get_send_mem_ptr(), 0, bytes_to_pad);
- num_bytes_committed += bytes_to_pad;
- commit_send_buff();
+ //calculate the number of bytes to alignment
+ size_t bytes_to_pad = (-1*curr_buff->offset)%alignment_padding;
+
+ //get the buffer, clear, and commit (really current buffer)
+ vrt_packet_handler::managed_send_buffs_t buffs(1);
+ if (this->get_send_buffs(buffs, 0.1)){
+ std::memset(buffs[0]->cast<void *>(), 0, bytes_to_pad);
+ buffs[0]->commit(bytes_to_pad);
+ }
}
/*!
- * Perform an actual commit on the send buffer:
- * Commit the contents of the send buffer and request a new buffer.
+ * Get a managed send buffer with the alignment padding:
+ * Always grab the next send buffer so we can timeout here.
*/
-void usrp1_impl::io_impl::commit_send_buff(void){
- send_buff->commit(num_bytes_committed);
- send_buff = data_transport->get_send_buff(send_timeout);
- num_bytes_committed = 0;
-}
-
bool usrp1_impl::io_impl::get_send_buffs(
vrt_packet_handler::managed_send_buffs_t &buffs, double timeout
){
- send_timeout = timeout;
UHD_ASSERT_THROW(buffs.size() == 1);
- //not enough bytes free -> use the pseudo buffer
- if (get_send_mem_size() < BYTES_PER_PACKET){
- buffs[0] = managed_send_buffer::make_safe(
- boost::asio::buffer(pseudo_buff),
- boost::bind(&usrp1_impl::io_impl::phony_commit_pseudo_buff, this, _1)
- );
- }
- //otherwise use the send buffer offset by the bytes written
- else{
- buffs[0] = managed_send_buffer::make_safe(
- boost::asio::buffer(get_send_mem_ptr(), get_send_mem_size()),
- boost::bind(&usrp1_impl::io_impl::phony_commit_send_buff, this, _1)
- );
- }
+ //try to get a new managed buffer with timeout
+ offset_send_buffer::sptr next_buff(offset_send_buffer::make(data_transport->get_send_buff(timeout)));
+ if (not next_buff->buff.get()) return false; /* propagate timeout here */
- return buffs[0].get() != NULL;
+ //calculate the buffer pointer and size given the offset
+ //references to the buffers are held in the bound function
+ buffs[0] = managed_send_buffer::make_safe(
+ boost::asio::buffer(
+ curr_buff->buff->cast<char *>() + curr_buff->offset,
+ curr_buff->buff->size() - curr_buff->offset
+ ),
+ boost::bind(&usrp1_impl::io_impl::commit_send_buff, this, curr_buff, next_buff, _1)
+ );
+
+ //store the next buffer for the next call
+ curr_buff = next_buff;
+
+ return true;
}
/***********************************************************************
@@ -182,6 +193,13 @@ static void usrp1_bs_vrt_packer(
if_packet_info.num_packet_words32 = if_packet_info.num_payload_words32;
}
+size_t usrp1_impl::get_max_send_samps_per_packet(void) const {
+ return (_data_transport->get_send_frame_size() - alignment_padding)
+ / _tx_otw_type.get_sample_size()
+ / _tx_subdev_spec.size()
+ ;
+}
+
size_t usrp1_impl::send(
const std::vector<const void *> &buffs, size_t num_samps,
const tx_metadata_t &metadata, const io_type_t &io_type,
@@ -249,6 +267,13 @@ static bool get_recv_buffs(
return buffs[0].get() != NULL;
}
+size_t usrp1_impl::get_max_recv_samps_per_packet(void) const {
+ return _data_transport->get_recv_frame_size()
+ / _rx_otw_type.get_sample_size()
+ / _rx_subdev_spec.size()
+ ;
+}
+
size_t usrp1_impl::recv(
const std::vector<void *> &buffs, size_t num_samps,
rx_metadata_t &metadata, const io_type_t &io_type,
diff --git a/host/lib/usrp/usrp1/usrp1_impl.hpp b/host/lib/usrp/usrp1/usrp1_impl.hpp
index f2c464610..ff4d40762 100644
--- a/host/lib/usrp/usrp1/usrp1_impl.hpp
+++ b/host/lib/usrp/usrp1/usrp1_impl.hpp
@@ -90,15 +90,9 @@ public:
const uhd::io_type_t &,
recv_mode_t, double);
- static const size_t BYTES_PER_PACKET = 512*4; //under the transfer size
+ size_t get_max_send_samps_per_packet(void) const;
- size_t get_max_send_samps_per_packet(void) const {
- return BYTES_PER_PACKET/_tx_otw_type.get_sample_size()/_tx_subdev_spec.size();
- }
-
- size_t get_max_recv_samps_per_packet(void) const {
- return BYTES_PER_PACKET/_rx_otw_type.get_sample_size()/_rx_subdev_spec.size();
- }
+ size_t get_max_recv_samps_per_packet(void) const;
bool recv_async_msg(uhd::async_metadata_t &, double);
--
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