Add "OS2_" prefixes to exported procedure names. Implement "readahead

buffer" abstraction.

diff --git a/v7/src/microcode/os2cthrd.c b/v7/src/microcode/os2cthrd.c
index 863534d063bac577b3f3acaff820fc98f9256819..368b5ee8b9d6708ad0de58c5d975fb87b9ce16b9 100644 (file)
--- a/v7/src/microcode/os2cthrd.c
+++ b/v7/src/microcode/os2cthrd.c
@@ -1,6 +1,6 @@
 /* -*-C-*-
 
-$Id: os2cthrd.c,v 1.1 1994/11/28 03:42:55 cph Exp $
+$Id: os2cthrd.c,v 1.2 1994/12/02 20:41:49 cph Exp $
 
 Copyright (c) 1994 Massachusetts Institute of Technology
 
@@ -35,7 +35,10 @@ MIT in each case. */
 /* Scheme side of channel thread interface */
 
 #include "os2.h"
-\f
+
+static msg_list_t * new_list (void);
+static msg_t * new_message (void);
+
 void
 OS2_initialize_channel_thread_messages (void)
 {
@@ -55,8 +58,20 @@ OS2_make_channel_context (void)
   return (context);
 }
 
+void
+OS2_channel_thread_close (Tchannel channel)
+{
+  channel_context_t * context = (CHANNEL_OPERATOR_CONTEXT (channel));
+  /* Closing handle should force input thread to kill itself.  */
+  STD_API_CALL (dos_close, (CHANNEL_HANDLE (channel)));
+  if ((CHANNEL_CONTEXT_READAHEAD (context)) != 0)
+    OS2_destroy_message (CHANNEL_CONTEXT_READAHEAD (context));
+  OS2_close_qid (CHANNEL_CONTEXT_READER_QID (context));
+  OS_free (context);
+}
+\f
 long
-channel_thread_read (Tchannel channel, char * buffer, size_t size)
+OS2_channel_thread_read (Tchannel channel, char * buffer, size_t size)
 {
   channel_context_t * context = (CHANNEL_OPERATOR_CONTEXT (channel));
   qid_t qid = (CHANNEL_CONTEXT_READER_QID (context));
@@ -118,20 +133,110 @@ OS2_wait_for_readahead_ack (qid_t qid)
 {
   /* Wait for an acknowledgement before starting another read.
      This regulates the amount of data in the queue.  */
-  msg_t * message = (OS2_receive_message (qid, 1));
-  if ((MSG_TYPE (message)) != mt_readahead_ack)
-    OS2_logic_error ("Expected readahead_ack message.");
-  OS2_destroy_message (message);
+  OS2_destroy_message (OS2_wait_for_message (qid, mt_readahead_ack));
+}
+\f
+readahead_buffer_t *
+OS2_make_readahead_buffer (void)
+{
+  readahead_buffer_t * buffer = (OS_malloc (sizeof (readahead_buffer_t)));
+  (buffer -> head) = 0;
+  (buffer -> tail) = 0;
+  return (buffer);
+}
+
+int
+OS2_readahead_buffer_emptyp (readahead_buffer_t * buffer)
+{
+  return ((buffer -> head) == 0);
 }
 
 void
-channel_thread_close (Tchannel channel)
+OS2_readahead_buffer_insert (readahead_buffer_t * buffer, char c)
 {
-  channel_context_t * context = (CHANNEL_OPERATOR_CONTEXT (channel));
-  /* Closing handle should force input thread to kill itself.  */
-  STD_API_CALL (dos_close, (CHANNEL_HANDLE (channel)));
-  if ((CHANNEL_CONTEXT_READAHEAD (context)) != 0)
-    OS2_destroy_message (CHANNEL_CONTEXT_READAHEAD (context));
-  OS2_close_qid (CHANNEL_CONTEXT_READER_QID (context));
-  OS_free (context);
+  if ((buffer -> head) == 0)
+    {
+      msg_list_t * tail = (new_list ());
+      (buffer -> head) = tail;
+      (buffer -> tail) = tail;
+    }
+  else if ((SM_READAHEAD_SIZE ((buffer -> tail) -> message))
+          == SM_READAHEAD_MAX)
+    {
+      msg_list_t * tail = (new_list ());
+      ((buffer -> tail) -> next) = tail;
+      (buffer -> tail) = tail;
+    }
+  {
+    msg_t * message = ((buffer -> tail) -> message);
+    ((SM_READAHEAD_DATA (message)) [(SM_READAHEAD_SIZE (message))++]) = c;
+  }
+}
+
+static msg_list_t *
+new_list (void)
+{
+  msg_list_t * cell = (OS_malloc (sizeof (msg_list_t)));
+  (cell -> message) = (new_message ());
+  (cell -> next) = 0;
+  return (cell);
+}
+
+static msg_t *
+new_message (void)
+{
+  msg_t * message = (OS2_make_readahead ());
+  (SM_READAHEAD_SIZE (message)) = 0;
+  return (message);
+}
+\f
+char
+OS2_readahead_buffer_rubout (readahead_buffer_t * buffer)
+{
+  if ((buffer -> head) == 0)
+    OS2_logic_error ("Rubout from empty readahead buffer.");
+  {
+    msg_t * message = ((buffer -> tail) -> message);
+    char c = ((SM_READAHEAD_DATA (message)) [--(SM_READAHEAD_SIZE (message))]);
+    if ((SM_READAHEAD_SIZE (message)) == 0)
+      {
+       msg_list_t * tail = (buffer -> tail);
+       msg_list_t * prev = (buffer -> head);
+       if (prev == tail)
+         (buffer -> head) = 0;
+       else
+         {
+           while ((prev -> next) != tail)
+             prev = (prev -> next);
+           (prev -> next) = 0;
+           (buffer -> tail) = prev;
+         }
+       OS_free (tail);
+      }
+    OS2_destroy_message (message);
+    return (c);
+  }
+}
+
+msg_t *
+OS2_readahead_buffer_read (readahead_buffer_t * buffer)
+{
+  msg_list_t * head = (buffer -> head);
+  if (head == 0)
+    return (new_message ());
+  else
+    {
+      msg_t * message = (head -> message);
+      (buffer -> head) = (head -> next);
+      OS_free (head);
+      return (message);
+    }
+}
+
+msg_list_t *
+OS2_readahead_buffer_read_all (readahead_buffer_t * buffer)
+{
+  msg_list_t * head = (buffer -> head);
+  (buffer -> head) = 0;
+  return (head);
 }

diff --git a/v7/src/microcode/os2cthrd.h b/v7/src/microcode/os2cthrd.h
index 23d3470b5eb8be836adfd219969c586ecf92b27d..417d73a1ea56e0ec1ee6a913dc5f884197cc966c 100644 (file)
--- a/v7/src/microcode/os2cthrd.h
+++ b/v7/src/microcode/os2cthrd.h
@@ -1,6 +1,6 @@
 /* -*-C-*-
 
-$Id: os2cthrd.h,v 1.1 1994/11/28 03:42:55 cph Exp $
+$Id: os2cthrd.h,v 1.2 1994/12/02 20:41:38 cph Exp $
 
 Copyright (c) 1994 Massachusetts Institute of Technology
 
@@ -53,7 +53,7 @@ typedef struct
 #define CHANNEL_CONTEXT_READAHEAD_INDEX(c) ((c) -> readahead_index)
 #define CHANNEL_CONTEXT_EOFP(c) ((c) -> eofp)
 
-typedef struct
+typedef struct sm_readahead_s
 {
   DECLARE_MSG_HEADER_FIELDS;
   ULONG size;
@@ -68,8 +68,21 @@ typedef struct
 typedef msg_t sm_readahead_ack_t;
 
 extern channel_context_t * OS2_make_channel_context (void);
-extern long channel_thread_read (Tchannel, char *, size_t);
+extern long OS2_channel_thread_read (Tchannel, char *, size_t);
 extern void OS2_wait_for_readahead_ack (qid_t);
-extern void channel_thread_close (Tchannel);
+extern void OS2_channel_thread_close (Tchannel);
+
+typedef struct
+{
+  msg_list_t * head;
+  msg_list_t * tail;
+} readahead_buffer_t;
+
+extern readahead_buffer_t * OS2_make_readahead_buffer (void);
+extern int OS2_readahead_buffer_emptyp (readahead_buffer_t *);
+extern void OS2_readahead_buffer_insert (readahead_buffer_t *, char);
+extern char OS2_readahead_buffer_rubout (readahead_buffer_t *);
+extern msg_t * OS2_readahead_buffer_read (readahead_buffer_t *);
+extern msg_list_t * OS2_readahead_buffer_read_all (readahead_buffer_t *);
 
 #endif /* SCM_OS2CTHRD_H */

diff --git a/v7/src/microcode/os2pipe.c b/v7/src/microcode/os2pipe.c
index 50bfa22ea02f4f6067481a565068784dac9850ca..f2ec5edd67e4db255fb8718c3c24e62def596be7 100644 (file)
--- a/v7/src/microcode/os2pipe.c
+++ b/v7/src/microcode/os2pipe.c
@@ -1,6 +1,6 @@
 /* -*-C-*-
 
-$Id: os2pipe.c,v 1.1 1994/11/28 03:42:59 cph Exp $
+$Id: os2pipe.c,v 1.2 1994/12/02 20:41:57 cph Exp $
 
 Copyright (c) 1994 Massachusetts Institute of Technology
 
@@ -76,10 +76,11 @@ input_pipe_operator (Tchannel channel, chop_t operation,
     {
     case chop_read:
       (* ((long *) arg3))
-       = (channel_thread_read (channel, ((char *) arg1), ((size_t) arg2)));
+       = (OS2_channel_thread_read
+          (channel, ((char *) arg1), ((size_t) arg2)));
       break;
     case chop_close:
-      channel_thread_close (channel);
+      OS2_channel_thread_close (channel);
       break;
     default:
       OS2_logic_error ("Unknown operation for input pipe.");