From fedfc3443de7adacb290cc33adb4b8fb63739e41 Mon Sep 17 00:00:00 2001
From: Christian Groessler <chris@groessler.org>
Date: Fri, 24 Feb 2023 02:12:19 +0100
Subject: [PATCH] fix for issue #1973 (printf("%c", '\0') doesn't _write '\0'
 to fd 0)

---
 libsrc/common/_printf.s | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/libsrc/common/_printf.s b/libsrc/common/_printf.s
index 840d42127..a0074583e 100644
--- a/libsrc/common/_printf.s
+++ b/libsrc/common/_printf.s
@@ -502,10 +502,10 @@ DoFormat:
 ; It is a character
 
         jsr     GetIntArg               ; Get the argument (promoted to int)
-        sta     Buf                     ; Place it as zero terminated string...
-        lda     #0
-        sta     Buf+1                   ; ...into the buffer
-        jmp     HaveArg                 ; Done
+        sta     Buf                     ; Place it into the buffer
+        ldx     #0
+        lda     #1                      ; Buffer length is 1
+        jmp     HaveArg1
 
 ; Is it an integer?
 
@@ -671,6 +671,7 @@ HaveArg:
         lda     Str
         ldx     Str+1
         jsr     _strlen                 ; Get length of argument
+HaveArg1:                               ; Jumped into here from %c handling
         sta     ArgLen
         stx     ArgLen+1