3 * Copyright (c) 2009, Microsoft Corporation.
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms and conditions of the GNU General Public License,
7 * version 2, as published by the Free Software Foundation.
9 * This program is distributed in the hope it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
14 * You should have received a copy of the GNU General Public License along with
15 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
16 * Place - Suite 330, Boston, MA 02111-1307 USA.
19 * Haiyang Zhang <haiyangz@microsoft.com>
20 * Hank Janssen <hjanssen@microsoft.com>
25 #include "include/logging.h"
26 #include "RingBuffer.h"
32 // Amount of space to write to
33 #define BYTES_AVAIL_TO_WRITE(r, w, z) ((w) >= (r))?((z) - ((w) - (r))):((r) - (w))
39 GetRingBufferAvailBytes()
42 Get number of bytes available to read and to write to
43 for the specified ring buffer
47 GetRingBufferAvailBytes(RING_BUFFER_INFO *rbi, u32 *read, u32 *write)
49 u32 read_loc,write_loc;
51 // Capture the read/write indices before they changed
52 read_loc = rbi->RingBuffer->ReadIndex;
53 write_loc = rbi->RingBuffer->WriteIndex;
55 *write = BYTES_AVAIL_TO_WRITE(read_loc, write_loc, rbi->RingDataSize);
56 *read = rbi->RingDataSize - *write;
62 GetNextWriteLocation()
65 Get the next write location for the specified ring buffer
69 GetNextWriteLocation(RING_BUFFER_INFO* RingInfo)
71 u32 next = RingInfo->RingBuffer->WriteIndex;
73 ASSERT(next < RingInfo->RingDataSize);
81 SetNextWriteLocation()
84 Set the next write location for the specified ring buffer
88 SetNextWriteLocation(RING_BUFFER_INFO* RingInfo, u32 NextWriteLocation)
90 RingInfo->RingBuffer->WriteIndex = NextWriteLocation;
99 Get the next read location for the specified ring buffer
103 GetNextReadLocation(RING_BUFFER_INFO* RingInfo)
105 u32 next = RingInfo->RingBuffer->ReadIndex;
107 ASSERT(next < RingInfo->RingDataSize);
115 GetNextReadLocationWithOffset()
118 Get the next read location + offset for the specified ring buffer.
119 This allows the caller to skip
123 GetNextReadLocationWithOffset(RING_BUFFER_INFO* RingInfo, u32 Offset)
125 u32 next = RingInfo->RingBuffer->ReadIndex;
127 ASSERT(next < RingInfo->RingDataSize);
129 next %= RingInfo->RingDataSize;
137 SetNextReadLocation()
140 Set the next read location for the specified ring buffer
144 SetNextReadLocation(RING_BUFFER_INFO* RingInfo, u32 NextReadLocation)
146 RingInfo->RingBuffer->ReadIndex = NextReadLocation;
156 Get the start of the ring buffer
160 GetRingBuffer(RING_BUFFER_INFO* RingInfo)
162 return (void *)RingInfo->RingBuffer->Buffer;
172 Get the size of the ring buffer
176 GetRingBufferSize(RING_BUFFER_INFO* RingInfo)
178 return RingInfo->RingDataSize;
184 GetRingBufferIndices()
187 Get the read and write indices as UINT64 of the specified ring buffer
191 GetRingBufferIndices(RING_BUFFER_INFO* RingInfo)
193 return ((UINT64)RingInfo->RingBuffer->WriteIndex << 32) || RingInfo->RingBuffer->ReadIndex;
203 Dump out to console the ring buffer info
207 DumpRingInfo(RING_BUFFER_INFO* RingInfo, char *Prefix)
209 u32 bytesAvailToWrite;
210 u32 bytesAvailToRead;
212 GetRingBufferAvailBytes(RingInfo, &bytesAvailToRead, &bytesAvailToWrite);
214 DPRINT(VMBUS, DEBUG_RING_LVL, "%s <<ringinfo %p buffer %p avail write %u avail read %u read idx %u write idx %u>>",
217 RingInfo->RingBuffer->Buffer,
220 RingInfo->RingBuffer->ReadIndex,
221 RingInfo->RingBuffer->WriteIndex);
229 RING_BUFFER_INFO *RingInfo,
230 u32 StartWriteOffset,
236 RING_BUFFER_INFO *RingInfo,
239 u32 StartReadOffset);
246 RingBufferGetDebugInfo()
249 Get various debug metrics for the specified ring buffer
253 RingBufferGetDebugInfo(
254 RING_BUFFER_INFO *RingInfo,
255 RING_BUFFER_DEBUG_INFO *DebugInfo
258 u32 bytesAvailToWrite;
259 u32 bytesAvailToRead;
261 if (RingInfo->RingBuffer)
263 GetRingBufferAvailBytes(RingInfo, &bytesAvailToRead, &bytesAvailToWrite);
265 DebugInfo->BytesAvailToRead = bytesAvailToRead;
266 DebugInfo->BytesAvailToWrite = bytesAvailToWrite;
267 DebugInfo->CurrentReadIndex = RingInfo->RingBuffer->ReadIndex;
268 DebugInfo->CurrentWriteIndex = RingInfo->RingBuffer->WriteIndex;
270 DebugInfo->CurrentInterruptMask = RingInfo->RingBuffer->InterruptMask;
278 GetRingBufferInterruptMask()
281 Get the interrupt mask for the specified ring buffer
285 GetRingBufferInterruptMask(
286 RING_BUFFER_INFO *rbi
289 return rbi->RingBuffer->InterruptMask;
298 Initialize the ring buffer
303 RING_BUFFER_INFO *RingInfo,
308 ASSERT(sizeof(RING_BUFFER) == PAGE_SIZE);
310 memset(RingInfo, 0, sizeof(RING_BUFFER_INFO));
312 RingInfo->RingBuffer = (RING_BUFFER*)Buffer;
313 RingInfo->RingBuffer->ReadIndex = RingInfo->RingBuffer->WriteIndex = 0;
315 RingInfo->RingSize = BufferLen;
316 RingInfo->RingDataSize = BufferLen - sizeof(RING_BUFFER);
318 RingInfo->RingLock = SpinlockCreate();
329 Cleanup the ring buffer
334 RING_BUFFER_INFO* RingInfo
337 SpinlockClose(RingInfo->RingLock);
346 Write to the ring buffer
351 RING_BUFFER_INFO* OutRingInfo,
352 SG_BUFFER_LIST SgBuffers[],
357 u32 byteAvailToWrite;
359 u32 totalBytesToWrite=0;
361 volatile u32 nextWriteLocation;
362 UINT64 prevIndices=0;
366 for (i=0; i < SgBufferCount; i++)
368 totalBytesToWrite += SgBuffers[i].Length;
371 totalBytesToWrite += sizeof(UINT64);
373 SpinlockAcquire(OutRingInfo->RingLock);
375 GetRingBufferAvailBytes(OutRingInfo, &byteAvailToRead, &byteAvailToWrite);
377 DPRINT_DBG(VMBUS, "Writing %u bytes...", totalBytesToWrite);
379 //DumpRingInfo(OutRingInfo, "BEFORE ");
381 // If there is only room for the packet, assume it is full. Otherwise, the next time around, we think the ring buffer
382 // is empty since the read index == write index
383 if (byteAvailToWrite <= totalBytesToWrite)
385 DPRINT_DBG(VMBUS, "No more space left on outbound ring buffer (needed %u, avail %u)", totalBytesToWrite, byteAvailToWrite);
387 SpinlockRelease(OutRingInfo->RingLock);
394 // Write to the ring buffer
395 nextWriteLocation = GetNextWriteLocation(OutRingInfo);
397 for (i=0; i < SgBufferCount; i++)
399 nextWriteLocation = CopyToRingBuffer(OutRingInfo,
402 SgBuffers[i].Length);
405 // Set previous packet start
406 prevIndices = GetRingBufferIndices(OutRingInfo);
408 nextWriteLocation = CopyToRingBuffer(OutRingInfo,
413 // Make sure we flush all writes before updating the writeIndex
416 // Now, update the write location
417 SetNextWriteLocation(OutRingInfo, nextWriteLocation);
419 //DumpRingInfo(OutRingInfo, "AFTER ");
421 SpinlockRelease(OutRingInfo->RingLock);
435 Read without advancing the read index
440 RING_BUFFER_INFO* InRingInfo,
445 u32 bytesAvailToWrite;
446 u32 bytesAvailToRead;
447 u32 nextReadLocation=0;
449 SpinlockAcquire(InRingInfo->RingLock);
451 GetRingBufferAvailBytes(InRingInfo, &bytesAvailToRead, &bytesAvailToWrite);
453 // Make sure there is something to read
454 if (bytesAvailToRead < BufferLen )
456 //DPRINT_DBG(VMBUS, "got callback but not enough to read <avail to read %d read size %d>!!", bytesAvailToRead, BufferLen);
458 SpinlockRelease(InRingInfo->RingLock);
463 // Convert to byte offset
464 nextReadLocation = GetNextReadLocation(InRingInfo);
466 nextReadLocation = CopyFromRingBuffer(InRingInfo,
471 SpinlockRelease(InRingInfo->RingLock);
483 Read and advance the read index
488 RING_BUFFER_INFO* InRingInfo,
494 u32 bytesAvailToWrite;
495 u32 bytesAvailToRead;
496 u32 nextReadLocation=0;
497 UINT64 prevIndices=0;
499 ASSERT(BufferLen > 0);
501 SpinlockAcquire(InRingInfo->RingLock);
503 GetRingBufferAvailBytes(InRingInfo, &bytesAvailToRead, &bytesAvailToWrite);
505 DPRINT_DBG(VMBUS, "Reading %u bytes...", BufferLen);
507 //DumpRingInfo(InRingInfo, "BEFORE ");
509 // Make sure there is something to read
510 if (bytesAvailToRead < BufferLen )
512 DPRINT_DBG(VMBUS, "got callback but not enough to read <avail to read %d read size %d>!!", bytesAvailToRead, BufferLen);
514 SpinlockRelease(InRingInfo->RingLock);
519 nextReadLocation = GetNextReadLocationWithOffset(InRingInfo, Offset);
521 nextReadLocation = CopyFromRingBuffer(InRingInfo,
526 nextReadLocation = CopyFromRingBuffer(InRingInfo,
531 // Make sure all reads are done before we update the read index since
532 // the writer may start writing to the read area once the read index is updated
535 // Update the read index
536 SetNextReadLocation(InRingInfo, nextReadLocation);
538 //DumpRingInfo(InRingInfo, "AFTER ");
540 SpinlockRelease(InRingInfo->RingLock);
552 Helper routine to copy from source to ring buffer.
553 Assume there is enough room. Handles wrap-around in dest case only!!
558 RING_BUFFER_INFO *RingInfo,
559 u32 StartWriteOffset,
563 void * ringBuffer=GetRingBuffer(RingInfo);
564 u32 ringBufferSize=GetRingBufferSize(RingInfo);
567 if (SrcLen > ringBufferSize - StartWriteOffset) // wrap-around detected!
569 DPRINT_DBG(VMBUS, "wrap-around detected!");
571 fragLen = ringBufferSize - StartWriteOffset;
572 memcpy(ringBuffer + StartWriteOffset, Src, fragLen);
573 memcpy(ringBuffer, Src + fragLen, SrcLen - fragLen);
577 memcpy(ringBuffer + StartWriteOffset, Src, SrcLen);
580 StartWriteOffset += SrcLen;
581 StartWriteOffset %= ringBufferSize;
583 return StartWriteOffset;
593 Helper routine to copy to source from ring buffer.
594 Assume there is enough room. Handles wrap-around in src case only!!
599 RING_BUFFER_INFO *RingInfo,
604 void * ringBuffer=GetRingBuffer(RingInfo);
605 u32 ringBufferSize=GetRingBufferSize(RingInfo);
609 if (DestLen > ringBufferSize - StartReadOffset) // wrap-around detected at the src
611 DPRINT_DBG(VMBUS, "src wrap-around detected!");
613 fragLen = ringBufferSize - StartReadOffset;
615 memcpy(Dest, ringBuffer + StartReadOffset, fragLen);
616 memcpy(Dest + fragLen, ringBuffer, DestLen - fragLen);
620 memcpy(Dest, ringBuffer + StartReadOffset, DestLen);
623 StartReadOffset += DestLen;
624 StartReadOffset %= ringBufferSize;
626 return StartReadOffset;