fix: fixes TAB routine

Author: boriel

src/arch/zx48k/library-asm/print.asm

@@ -232,20 +232,20 @@ __PRINT_TAB:
 
 __PRINT_TAB1:
     ld (MEM0), a
-    exx
     ld hl, __PRINT_TAB2
     jr __PRINT_SET_STATE
 
 __PRINT_TAB2:
     ld a, (MEM0)        ; Load tab code (ignore the current one)
-    push hl
-    push de
-    push bc
     ld hl, __PRINT_START
     ld (PRINT_JUMP_STATE), hl
+    exx
+    push hl
+    push bc
+    push de
     call PRINT_TAB
-    pop bc
     pop de
+    pop bc
     pop hl
     ret
 
@@ -496,6 +496,8 @@ PRINT_COMMA:
     add a, 16
 
 PRINT_TAB:
+    ; Tabulates the number of spaces in A register
+    ; If the current cursor position is already A, does nothing
     PROC
     LOCAL LOOP
 
@@ -507,11 +509,7 @@ PRINT_TAB:
     ld b, a
 LOOP:
     ld a, ' '
-    push bc
-    exx
     call __PRINTCHAR
-    exx
-    pop bc
     djnz LOOP
     ret
     ENDP

src/arch/zxnext/library-asm/print.asm

@@ -232,20 +232,20 @@ __PRINT_TAB:
 
 __PRINT_TAB1:
     ld (MEM0), a
-    exx
     ld hl, __PRINT_TAB2
     jr __PRINT_SET_STATE
 
 __PRINT_TAB2:
     ld a, (MEM0)        ; Load tab code (ignore the current one)
-    push hl
-    push de
-    push bc
     ld hl, __PRINT_START
     ld (PRINT_JUMP_STATE), hl
+    exx
+    push hl
+    push bc
+    push de
     call PRINT_TAB
-    pop bc
     pop de
+    pop bc
     pop hl
     ret
 
@@ -496,6 +496,8 @@ PRINT_COMMA:
     add a, 16
 
 PRINT_TAB:
+    ; Tabulates the number of spaces in A register
+    ; If the current cursor position is already A, does nothing
     PROC
     LOCAL LOOP
 
@@ -507,11 +509,7 @@ PRINT_TAB:
     ld b, a
 LOOP:
     ld a, ' '
-    push bc
-    exx
     call __PRINTCHAR
-    exx
-    pop bc
     djnz LOOP
     ret
     ENDP

tests/runtime/cases/print_tab.bas

@@ -3,12 +3,11 @@
 INIT("Testing TAB")
 
 f$=CHR(22,6,27,16,2,17,5,19,1,71) 'PRINT AT 6,27;"G"   - fine, so other control codes are not counted
-g$=CHR(22,7,10,17,0,23,31,0,32)   'PRINT AT 7,10; INK 0; TAB 31; " " last char is wrong. Should be a space
+g$=CHR(22,7,10,17,1,23,31,0,32)   'PRINT AT 7,10; INK 0; TAB 31; " " last char is wrong. Should be a space
 'PRINT AT 8,31;"-"                 'to measure the wrong positions
 'PRINT a$;b$;c$;d$;e$;f$;g$
 PRINT f$;g$;
 'PRINT AT 10,28;"HI"               'fine at same coords
 'PRINT AT 2,0;"--"                 'to measure the wrong positions
 
 FINISH
-