1 files changed, 284 insertions, 0 deletions

diff --git a/portmidi/pm_common/pmutil.c b/portmidi/pm_common/pmutil.c
new file mode 100755
index 0000000..a70fe2f
--- /dev/null
+++ b/portmidi/pm_common/pmutil.c
@@ -0,0 +1,284 @@
+/* pmutil.c -- some helpful utilities for building midi
+               applications that use PortMidi
+ */
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+#include "portmidi.h"
+#include "pmutil.h"
+#include "pminternal.h"
+
+#ifdef WIN32
+#define bzero(addr, siz) memset(addr, 0, siz)
+#endif
+
+// #define QUEUE_DEBUG 1
+#ifdef QUEUE_DEBUG
+#include "stdio.h"
+#endif
+
+typedef struct {
+    long head;
+    long tail;
+    long len;
+    long overflow;
+    int32_t msg_size; /* number of int32_t in a message including extra word */
+    int32_t peek_overflow;
+    int32_t *buffer;
+    int32_t *peek;
+    int32_t peek_flag;
+} PmQueueRep;
+
+
+PMEXPORT PmQueue *Pm_QueueCreate(long num_msgs, int32_t bytes_per_msg)
+{
+    int32_t int32s_per_msg = 
+            (int32_t) (((bytes_per_msg + sizeof(int32_t) - 1) &
+                       ~(sizeof(int32_t) - 1)) / sizeof(int32_t));
+    PmQueueRep *queue = (PmQueueRep *) pm_alloc(sizeof(PmQueueRep));
+    if (!queue) /* memory allocation failed */
+        return NULL;
+
+    /* need extra word per message for non-zero encoding */
+    queue->len = num_msgs * (int32s_per_msg + 1);
+    queue->buffer = (int32_t *) pm_alloc(queue->len * sizeof(int32_t));
+    bzero(queue->buffer, queue->len * sizeof(int32_t));
+    if (!queue->buffer) {
+        pm_free(queue);
+        return NULL;
+    } else { /* allocate the "peek" buffer */
+        queue->peek = (int32_t *) pm_alloc(int32s_per_msg * sizeof(int32_t));
+        if (!queue->peek) {
+            /* free everything allocated so far and return */
+            pm_free(queue->buffer);
+            pm_free(queue);
+            return NULL;
+        }
+    }
+    bzero(queue->buffer, queue->len * sizeof(int32_t));
+    queue->head = 0;
+    queue->tail = 0;
+    /* msg_size is in words */
+    queue->msg_size = int32s_per_msg + 1; /* note extra word is counted */
+    queue->overflow = FALSE;
+    queue->peek_overflow = FALSE;
+    queue->peek_flag = FALSE;
+    return queue;
+}
+
+
+PMEXPORT PmError Pm_QueueDestroy(PmQueue *q)
+{
+    PmQueueRep *queue = (PmQueueRep *) q;
+        
+    /* arg checking */
+    if (!queue || !queue->buffer || !queue->peek) 
+                return pmBadPtr;
+    
+    pm_free(queue->peek);
+    pm_free(queue->buffer);
+    pm_free(queue);
+    return pmNoError;
+}
+
+
+PMEXPORT PmError Pm_Dequeue(PmQueue *q, void *msg)
+{
+    long head;
+    PmQueueRep *queue = (PmQueueRep *) q;
+    int i;
+    int32_t *msg_as_int32 = (int32_t *) msg;
+
+    /* arg checking */
+    if (!queue)
+        return pmBadPtr;
+    /* a previous peek operation encountered an overflow, but the overflow
+     * has not yet been reported to client, so do it now. No message is
+     * returned, but on the next call, we will return the peek buffer.
+     */
+    if (queue->peek_overflow) {
+        queue->peek_overflow = FALSE;
+        return pmBufferOverflow;
+    }
+    if (queue->peek_flag) {
+        memcpy(msg, queue->peek, (queue->msg_size - 1) * sizeof(int32_t));
+        queue->peek_flag = FALSE;
+        return pmGotData;
+    }
+
+    head = queue->head;
+    /* if writer overflows, it writes queue->overflow = tail+1 so that
+     * when the reader gets to that position in the buffer, it can 
+     * return the overflow condition to the reader. The problem is that
+     * at overflow, things have wrapped around, so tail == head, and the
+     * reader will detect overflow immediately instead of waiting until
+     * it reads everything in the buffer, wrapping around again to the
+     * point where tail == head. So the condition also checks that
+     * queue->buffer[head] is zero -- if so, then the buffer is now
+     * empty, and we're at the point in the msg stream where overflow
+     * occurred. It's time to signal overflow to the reader. If 
+     * queue->buffer[head] is non-zero, there's a message there and we
+     * should read all the way around the buffer before signalling overflow.
+     * There is a write-order dependency here, but to fail, the overflow
+     * field would have to be written while an entire buffer full of 
+     * writes are still pending. I'm assuming out-of-order writes are
+     * possible, but not that many.
+     */
+    if (queue->overflow == head + 1 && !queue->buffer[head]) {
+        queue->overflow = 0; /* non-overflow condition */
+        return pmBufferOverflow;
+    }
+
+    /* test to see if there is data in the queue -- test from back
+     * to front so if writer is simultaneously writing, we don't
+     * waste time discovering the write is not finished 
+     */
+    for (i = queue->msg_size - 1; i >= 0; i--) {
+        if (!queue->buffer[head + i]) {
+            return pmNoData;
+        }
+    }
+    memcpy(msg, (char *) &queue->buffer[head + 1], 
+           sizeof(int32_t) * (queue->msg_size - 1));
+    /* fix up zeros */
+    i = queue->buffer[head];
+    while (i < queue->msg_size) {
+        int32_t j;
+        i--; /* msg does not have extra word so shift down */
+        j = msg_as_int32[i];
+        msg_as_int32[i] = 0;
+        i = j;
+    }
+    /* signal that data has been removed by zeroing: */
+    bzero((char *) &queue->buffer[head], sizeof(int32_t) * queue->msg_size);
+
+    /* update head */
+    head += queue->msg_size;
+    if (head == queue->len) head = 0;
+    queue->head = head;
+    return pmGotData; /* success */
+}
+
+
+
+PMEXPORT PmError Pm_SetOverflow(PmQueue *q)
+{
+    PmQueueRep *queue = (PmQueueRep *) q;
+    long tail;
+    /* arg checking */
+    if (!queue)
+        return pmBadPtr;
+    /* no more enqueue until receiver acknowledges overflow */
+    if (queue->overflow) return pmBufferOverflow;
+    tail = queue->tail;
+    queue->overflow = tail + 1;
+    return pmBufferOverflow;
+}
+
+
+PMEXPORT PmError Pm_Enqueue(PmQueue *q, void *msg)
+{
+    PmQueueRep *queue = (PmQueueRep *) q;
+    long tail;
+    int i;
+    int32_t *src = (int32_t *) msg;
+    int32_t *ptr;
+    int32_t *dest;
+    int rslt;
+    if (!queue) 
+        return pmBadPtr;
+    /* no more enqueue until receiver acknowledges overflow */
+    if (queue->overflow) return pmBufferOverflow;
+    rslt = Pm_QueueFull(q);
+    /* already checked above: if (rslt == pmBadPtr) return rslt; */
+    tail = queue->tail;
+    if (rslt) {
+        queue->overflow = tail + 1;
+        return pmBufferOverflow;
+    }
+
+    /* queue is has room for message, and overflow flag is cleared */
+    ptr = &queue->buffer[tail];
+    dest = ptr + 1;
+    for (i = 1; i < queue->msg_size; i++) {
+        int32_t j = src[i - 1];
+        if (!j) {
+            *ptr = i;
+            ptr = dest;
+        } else {
+            *dest = j;
+        }
+        dest++;
+    }
+    *ptr = i;
+    tail += queue->msg_size;
+    if (tail == queue->len) tail = 0;
+    queue->tail = tail;
+    return pmNoError;
+}
+
+
+PMEXPORT int Pm_QueueEmpty(PmQueue *q)
+{
+    PmQueueRep *queue = (PmQueueRep *) q;
+    return (!queue) ||  /* null pointer -> return "empty" */
+           (queue->buffer[queue->head] == 0 && !queue->peek_flag);
+}
+
+
+PMEXPORT int Pm_QueueFull(PmQueue *q)
+{
+    long tail;
+    int i; 
+    PmQueueRep *queue = (PmQueueRep *) q;
+    /* arg checking */
+    if (!queue)
+        return pmBadPtr;
+    tail = queue->tail;
+    /* test to see if there is space in the queue */
+    for (i = 0; i < queue->msg_size; i++) {
+        if (queue->buffer[tail + i]) {
+            return TRUE;
+        }
+    }
+    return FALSE;
+}
+
+
+PMEXPORT void *Pm_QueuePeek(PmQueue *q)
+{
+    PmError rslt;
+    int32_t temp;
+    PmQueueRep *queue = (PmQueueRep *) q;
+    /* arg checking */
+    if (!queue)
+        return NULL;
+
+    if (queue->peek_flag) {
+        return queue->peek;
+    }
+    /* this is ugly: if peek_overflow is set, then Pm_Dequeue() 
+     * returns immediately with pmBufferOverflow, but here, we
+     * want Pm_Dequeue() to really check for data. If data is
+     * there, we can return it
+     */
+    temp = queue->peek_overflow;
+    queue->peek_overflow = FALSE;
+    rslt = Pm_Dequeue(q, queue->peek);
+    queue->peek_overflow = temp;
+
+    if (rslt == 1) {
+        queue->peek_flag = TRUE;
+        return queue->peek;
+    } else if (rslt == pmBufferOverflow) {
+        /* when overflow is indicated, the queue is empty and the 
+         * first message that was dropped by Enqueue (signalling
+         * pmBufferOverflow to its caller) would have been the next
+         * message in the queue. Pm_QueuePeek will return NULL, but
+         * remember that an overflow occurred. (see Pm_Dequeue)
+         */
+        queue->peek_overflow = TRUE;
+    }
+    return NULL;
+}
+