Add support for DECBI

Author: gnachman

sources/VT100Grid.h

@@ -146,6 +146,7 @@
 // Scroll the scroll region down by one line.
 - (void)scrollDown;
 - (void)moveContentLeft;
+- (void)moveContentRight;
 
 // Clear scroll region, clear screen, move cursor and saved cursor to origin, leaving only the last
 // non-empty line at the top of the screen. Some lines may be left behind by giving a positive value

sources/VT100Grid.m

@@ -1229,6 +1229,18 @@ - (void)moveContentLeft {
     }
 }
 
+- (void)moveContentRight {
+    int x = 0;
+    if (self.useScrollRegionCols && self.cursorX >= self.leftMargin && self.cursorX <= self.rightMargin) {
+        // Cursor is within the scroll region so move the content within the scroll region.
+        x = self.leftMargin;
+    }
+    const screen_char_t c = [self defaultChar];
+    for (int i = self.topMargin; i <= self.bottomMargin; i++) {
+        [self insertChar:c externalAttributes:nil at:VT100GridCoordMake(x, i) times:1];
+    }
+}
+
 - (void)scrollRect:(VT100GridRect)rect downBy:(int)distance softBreak:(BOOL)softBreak {
     DLog(@"scrollRect:%d,%d %dx%d downBy:%d",
              rect.origin.x, rect.origin.y, rect.size.width, rect.size.height, distance);

sources/VT100OtherParser.m

@@ -126,6 +126,11 @@ + (void)decodeBytes:(unsigned char *)datap
             *rmlen = 2;
             break;
 
+        case '6':
+            result->type = VT100_DECBI;
+            *rmlen = 2;
+            break;
+
         case 'D':
             result->type = VT100CSI_IND;
             *rmlen = 2;

sources/VT100Screen.m

@@ -3656,6 +3656,16 @@ - (void)terminalForwardIndex {
     [delegate_ screenTriggerableChangeDidOccur];
 }
 
+- (void)terminalBackIndex {
+    if ((currentGrid_.cursorX == currentGrid_.leftMargin && ![self cursorOutsideLeftRightMargin] )||
+         currentGrid_.cursorX == 0) {
+        [currentGrid_ moveContentRight];
+    } else {
+        currentGrid_.cursorX -= 1;
+    }
+    [delegate_ screenTriggerableChangeDidOccur];
+}
+
 - (void)terminalResetPreservingPrompt:(BOOL)preservePrompt modifyContent:(BOOL)modifyContent {
     if (modifyContent) {
         const int linesToSave = [self numberOfLinesToPreserveWhenClearingScreen];

sources/VT100Terminal.m

@@ -1938,6 +1938,10 @@ - (void)executeToken:(VT100Token *)token {
             [self forwardIndex];
             break;
 
+        case VT100_DECBI:
+            [self backIndex];
+            break;
+
         case VT100CSI_PUSH_KEY_REPORTING_MODE:
             [self pushKeyReportingFlags:token.csi->p[0]];
             break;
@@ -3460,6 +3464,10 @@ - (void)forwardIndex {
     [self.delegate terminalForwardIndex];
 }
 
+- (void)backIndex {
+    [self.delegate terminalBackIndex];
+}
+
 - (void)executeANSIRequestMode:(int)mode {
     const iTermDECRPMSetting setting = [self settingForANSIRequestMode:mode];
     [self.delegate terminalSendReport:[self decrpmForMode:mode setting:setting ansi:YES]];

sources/VT100TerminalDelegate.h

@@ -120,8 +120,9 @@ typedef NS_ENUM(int, VT100TerminalColorIndex) {
 // Scroll up one line.
 - (void)terminalReverseIndex;
 
-// Move cursor to the right one column, scrolling content left if at margin.
+// Move cursor to the right/left one column, scrolling content left/right if at margin.
 - (void)terminalForwardIndex;
+- (void)terminalBackIndex;
 
 // Clear the screen, preserving the cursor's line.
 - (void)terminalResetPreservingPrompt:(BOOL)preservePrompt modifyContent:(BOOL)modifyContent;

sources/VT100Token.h

@@ -120,6 +120,7 @@ typedef enum {
     VT100CSI_DECRQM_DEC,            // Request Mode - Host To Terminal (DEC Private)
     VT100CSI_DECRQM_ANSI,           // Request Mode - Host To Terminal (ANSI)
     VT100_DECFI,                    // Forward Index
+    VT100_DECBI,                    // Back Index
 
     // https://sw.kovidgoyal.net/kitty/keyboard-protocol.html
     VT100CSI_PUSH_KEY_REPORTING_MODE,

sources/VT100Token.m

@@ -147,6 +147,7 @@ - (NSString *)codeName {
                           @(VT100CSI_DECRQM_DEC):             @"VT100CSI_DECRQM_DEC",
                           @(VT100CSI_DECRQM_ANSI):            @"VT100CSI_DECRQM_ANSI",
                           @(VT100_DECFI):                     @"VT100_DECFI",
+                          @(VT100_DECBI):                     @"VT100_DECBI",
                           @(VT100CSI_PUSH_KEY_REPORTING_MODE):@"VT100CSI_PUSH_KEY_REPORTING_MODE",
                           @(VT100CSI_POP_KEY_REPORTING_MODE): @"VT100CSI_POP_KEY_REPORTING_MODE",
                           @(VT100CSI_QUERY_KEY_REPORTING_MODE):@"VT100CSI_QUERY_KEY_REPORTING_MODE",

tests/decbi

@@ -0,0 +1,9 @@
+#!/bin/tcsh
+echo -n 'hi[?69hNow is the time for all good men to come to the aid of their party.'
+
+sleep 2
+while 1
+echo -n 6
+sleep 0.05
+end
+

tests/decfi

@@ -0,0 +1,9 @@
+#!/bin/tcsh
+echo -n 'hi[?69hNow is the time for all good men to come to the aid of their party.[?69l[?69h'
+
+sleep 2
+while 1
+echo -n 9
+sleep 0.05
+end
+