From efb8f9edf980ddee43fbdc3fbd47c6d718b46450 Mon Sep 17 00:00:00 2001
From: "Matthew R. Wilson" <mwilson@mattwilson.org>
Date: Sat, 11 Nov 2023 15:02:02 -0800
Subject: [PATCH] Update numeric validation patch and round out example1

---
 example1/example1.go | 22 ++++++++++++----------
 screen.go            | 17 ++++++++++-------
 2 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/example1/example1.go b/example1/example1.go
index 079cb2e..b4dbd73 100644
--- a/example1/example1.go
+++ b/example1/example1.go
@@ -33,8 +33,8 @@ var screen1 = go3270.Screen{
 	{Row: 6, Col: 0, Content: "Password  . . . ."},
 	{Row: 6, Col: 19, Name: "password", Write: true, Hidden: true},
 	{Row: 6, Col: 40}, // field "stop" character
-	{Row: 7, Col: 0, Content: "EmployeeId . . . ."},
-	{Row: 7, Col: 19, Name: "employeeId", Write: true, Highlighting: go3270.Underscore, NumericOnly: true},
+	{Row: 7, Col: 0, Content: "Employee ID . . ."},
+	{Row: 7, Col: 19, Name: "employeeID", Write: true, Highlighting: go3270.Underscore, NumericOnly: true},
 	{Row: 7, Col: 40}, // field "stop" character
 	{Row: 8, Col: 0, Content: "Press"},
 	{Row: 8, Col: 6, Intense: true, Content: "enter"},
@@ -50,14 +50,16 @@ var screen2 = go3270.Screen{
 	{Row: 4, Col: 19, Name: "fname"}, // We're giving this field a name to replace its value at runtime
 	{Row: 5, Col: 0, Content: "And your last name is"},
 	{Row: 5, Col: 22, Name: "lname"}, // We're giving this field a name to replace its value at runtime
-	{Row: 6, Col: 0, Name: "passwordOutput"},
-	{Row: 8, Col: 0, Content: "Press"},
-	{Row: 8, Col: 6, Intense: true, Content: "enter"},
-	{Row: 8, Col: 12, Content: "to enter your name again, or"},
-	{Row: 8, Col: 41, Intense: true, Content: "PF3"},
-	{Row: 8, Col: 45, Content: "to quit and disconnect."},
-	{Row: 11, Col: 0, Color: go3270.Turquoise, Highlighting: go3270.ReverseVideo, Content: "Here is a field with extended attributes."},
-	{Row: 11, Col: 42}, // remember to "stop" fields with a regular field, to clear the reverse video for example
+	{Row: 6, Col: 0, Content: "And your employeed ID is"},
+	{Row: 6, Col: 22, Name: "employeeID"}, // We're giving this field a name to replace its value at runtime
+	{Row: 7, Col: 0, Name: "passwordOutput"},
+	{Row: 9, Col: 0, Content: "Press"},
+	{Row: 9, Col: 6, Intense: true, Content: "enter"},
+	{Row: 9, Col: 12, Content: "to enter your name again, or"},
+	{Row: 9, Col: 41, Intense: true, Content: "PF3"},
+	{Row: 9, Col: 45, Content: "to quit and disconnect."},
+	{Row: 12, Col: 0, Color: go3270.Turquoise, Highlighting: go3270.ReverseVideo, Content: "Here is a field with extended attributes."},
+	{Row: 12, Col: 42}, // remember to "stop" fields with a regular field, to clear the reverse video for example
 	{Row: 22, Col: 0, Content: "PF3 Exit"},
 }
 
diff --git a/screen.go b/screen.go
index c65a615..1d4e107 100644
--- a/screen.go
+++ b/screen.go
@@ -40,7 +40,9 @@ type Field struct {
 	// password input field).
 	Hidden bool
 
-	// NumericOnly if set only allows numeric input to be written to the field
+	// NumericOnly indicates that only numbers may be entered into the field.
+	// Very fiew 3270 clients support this, so you must always still validate
+	// the input on the server side.
 	NumericOnly bool
 
 	// Color is the field color. The default value is the default color.
@@ -196,7 +198,8 @@ func buildField(f Field) []byte {
 	if f.Color == DefaultColor && f.Highlighting == DefaultHighlight {
 		// this is a traditional field, issue a normal sf command
 		buf.WriteByte(0x1d) // sf - "start field"
-		buf.WriteByte(sfAttribute(f.Write, f.Intense, f.Hidden, f.Autoskip, f.NumericOnly))
+		buf.WriteByte(sfAttribute(f.Write, f.Intense, f.Hidden, f.Autoskip,
+			f.NumericOnly))
 		return buf.Bytes()
 	}
 
@@ -213,7 +216,8 @@ func buildField(f Field) []byte {
 
 	// Write the basic field attribute
 	buf.WriteByte(0xc0)
-	buf.WriteByte(sfAttribute(f.Write, f.Intense, f.Hidden, f.Autoskip, f.NumericOnly))
+	buf.WriteByte(sfAttribute(f.Write, f.Intense, f.Hidden, f.Autoskip,
+		f.NumericOnly))
 
 	// Write the highlighting attribute
 	if f.Highlighting != DefaultHighlight {
@@ -242,7 +246,9 @@ func sfAttribute(write, intense, hidden, skip, numeric bool) byte {
 		// The MDT bit -- we always want writable field values returned,
 		// even if unchanged
 		attribute |= 1 // set "bit 7"
-
+		if numeric {
+			attribute |= 1 << 4 // set "bit 3"
+		}
 	}
 	if intense {
 		attribute |= 1 << 3 // set "bit 4"
@@ -251,9 +257,6 @@ func sfAttribute(write, intense, hidden, skip, numeric bool) byte {
 		attribute |= 1 << 3 // set "bit 4"
 		attribute |= 1 << 2 // set "bit 5"
 	}
-	if numeric {
-		attribute |= 1 << 4 // set "bit 3"
-	}
 	// Fill in top 2 bits with appropriate values
 	attribute = codes[attribute]
 	return attribute