Rethink suspend mode: FIFO always freewheels.

2 files changed, 38 insertions, 48 deletions

diff --git a/pw.1 b/pw.1
index e33e2e4..ffcd6ff 100644
--- a/pw.1
+++ b/pw.1
@@ -143,18 +143,18 @@ Scroll the display to the right.
 Reset scroll to first column.
 
 .IP \fISpace\fP
-Suspend the entry of lines of new lines of input into the display FIFO.
-In suspended mode, input continues to be read from the pipe, but is discarded.
-The status string
+Suspend the refresh of the display.  In suspended mode, input continues to pass
+through the FIFO, but all display refresh is stopped. The status indicator
 .B SUSPENDED
-is displayed below the data.
+is displayed below the data. If the the status is already
+.B EOF
+then suspend mode cannot be entered.
 
 .IP \fIEnter\fP
-Cancel suspended mode, and resume adding data to the FIFO. The
+Cancel suspended mode, resuming display refresh. The display is refreshed
+immediately and the
 .B SUSPENDED
-status string disappears. If the status is already
-.B EOF
-then suspend mode cannot be entered.
+status indicator disappears.
 
 .IP \fB:\fP
 Enter colon command mode. In colon command mode, the status line clears
@@ -176,22 +176,22 @@ are documented in the COLON COMMANDS section below.
 
 .SH COLON COMMANDS
 
-First, some general remarks. the current contents of the FIFO buffer may have
-changed relative to what is displayed on the screen. The space between the
-command and the argument may be omitted. The command is replaced with
-a result string, which persists over the poll interval period. The longer
-the poll interval
+First, some general remarks. Display refresh doesn't pause during the editing
+of a colon command. If that is required, the suspend command must be used.
+The space between the command and the argument may be omitted. After a command
+is executed, a result message appears in its place.  This message persists over
+the poll interval period. The longer the poll interval
 .RB ( -i " option),
 the longer the result message persists.
 
 .IP "\fB:w\fP \fIfilename\fP"
-Write the current contents of the FIFO buffer into the specified file.
+Write the current contents of the display into the specified file.
 
 .IP "\fB:a\fP \fIfilename\fP"
-Append the current contents of the FIFO buffer into the specified file.
+Append the current contents of the display into the specified file.
 
 .IP "\fB:!\fP \fIfilename\fP"
-Pipe the current contents of the FIFO buffers into the specified command.
+Pipe the current contents of of the display into the specified command.
 .PP
 Any other command results in a brief error message.
 
@@ -274,9 +274,6 @@ terminal abstraction library/data.
 
 The intervals and number of lines cannot be dynamically adjusted.
 
-Suspend mode is confusing; it doesn't necessarily freeze what is on the
-screen.
-
 There is no support for unwrapping long lines, which would be useful for
 copy and paste.
 
@@ -286,6 +283,8 @@ During the
 .B :!
 command's execution, the TTY settings are not restored.
 
+Most of these issues are easy; patches welcome.
+
 .SH AUTHOR
 Kaz Kylheku <kaz@kylheku.com>
 
diff --git a/pw.c b/pw.c
index d0990d2..ecc37c5 100644
--- a/pw.c
+++ b/pw.c
@@ -192,15 +192,19 @@ static void drawstatus(unsigned stat, char *cmd)
 static void redraw(char **circbuf, int nlines, int hpos,
                    int columns, unsigned stat, char *cmd)
 {
-  if (snapshot) {
-    for (int i = 0; i < snaplines; i++)
-     dsdrop(snapshot[i]);
-  }
-  snaplines = nlines;
-  printf("\r\033[%dA\033[J", nlines);
-  for (int i = 0; i < nlines; i++) {
-    drawline(circbuf[i], hpos, columns);
-    snapshot[i] = dsref(circbuf[i]);
+  if ((stat & stat_susp) == 0) {
+    if (snapshot) {
+      for (int i = 0; i < snaplines; i++)
+       dsdrop(snapshot[i]);
+    }
+    snaplines = nlines;
+    printf("\r\033[%dA\033[J", nlines);
+    for (int i = 0; i < nlines; i++) {
+      drawline(circbuf[i], hpos, columns);
+      snapshot[i] = dsref(circbuf[i]);
+    }
+  } else {
+    clear_cur_line();
   }
   drawstatus(stat, cmd);
 }
@@ -391,19 +395,13 @@ int main(int argc, char **argv)
       if ((stat & stat_eof) == 0 && pe[1].revents) {
         if ((line = getln(stdin))) {
           if (nlines == maxlines) {
-            if ((stat & stat_susp)) {
-              dsdrop(line);
-            } else {
-              dsdrop(circbuf[0]);
-              memmove(circbuf, circbuf + 1, (nlines - 1) * sizeof *circbuf);
-              circbuf[nlines - 1] = line;
-              stat |= stat_dirty;
-            }
+            dsdrop(circbuf[0]);
+            memmove(circbuf, circbuf + 1, (nlines - 1) * sizeof *circbuf);
+            circbuf[nlines - 1] = line;
+            stat |= stat_dirty;
           } else {
-            if ((stat & stat_susp)) {
-              dsdrop(line);
-            } else {
-              circbuf[nlines++] = line;
+            circbuf[nlines++] = line;
+            if ((stat & stat_susp) == 0) {
               snapshot[snaplines++] = dsref(line);
               clear_cur_line();
               drawline(line, hpos, columns);
@@ -455,15 +453,8 @@ int main(int argc, char **argv)
             stat |= stat_dirty;
             break;
           case ' ':
-            if ((stat & stat_eof) == 0) {
+            if ((stat & stat_eof) == 0)
               stat |= (stat_dirty | stat_susp);
-              for (int i = 0; i < nlines || i < snaplines; i++) {
-                if (i < nlines)
-                  dsdrop(circbuf[i]);
-                circbuf[i] = (i < snaplines) ? dsref(snapshot[i]) : 0;
-              }
-              nlines = snaplines;
-            }
             break;
           case 13:
             stat &= ~stat_susp;