From 30e15a269edc9407c44806aeda007d815ed0c130 Mon Sep 17 00:00:00 2001
From: Curtis F Kaylor <revcurtis@gmail.com>
Date: Sun, 28 Jan 2018 14:29:22 -0500
Subject: [PATCH] Removed ptrsav() and ptrrst() from pointer library

---
 doc/pointer.txt     | 37 +++++++++++--------------------------
 include/pointer.a02 | 25 +------------------------
 include/pointer.h02 |  8 --------
 vic20/pointers.c02  | 15 +++++++--------
 4 files changed, 19 insertions(+), 66 deletions(-)

diff --git a/doc/pointer.txt b/doc/pointer.txt
index a2abcd6..9674656 100644
--- a/doc/pointer.txt
+++ b/doc/pointer.txt
@@ -6,7 +6,13 @@ These functions are intended to allow sequential reading and writing of
 individual bytes to arbitrary locations in memory. 
 
 Only one pointer may be active at a time, but it's contents may be saved 
-and restored. 
+and restored using the following code:
+
+  savelo = ptrlo; savehi = ptrhi; //save current pointer
+  ptrlo = savelo; ptrhi = savehi; //restore current pointer
+  
+where savelo and savehi are an arbitrary pair of variables defined in the
+program. 
 
 Note: There is no concept of a null pointer in C02. A pointer containing
 the value 0 simply points to the first byte of memory. 
@@ -106,34 +112,13 @@ The following application functions are defined:
                       
                       Note: Sets variables srclo and srchi.
 
-  ptrsav(&r);         Pointer Save: Copies the pointer contents into the
-                      first to bytes of array r.
 
-                      This is roughly equivalent to the C code
-                      
-                        r = (int) p;
-                       
-                      
-                      Note: Sets variables srclo, srchi, and temp0.
+Note: This library expects the following to be defined: 
 
-  ptrrst(&r);         Pointer Restore: Copies the first to bytes of array r 
-                      into the pointer contents.
-
-                      This is roughly equivalent to the C code
-                      
-                        p = (void*) r;
-                       
-                      Note: Sets variables srclo, srchi, ptrlo, and ptrhi.
-
-Note: This library expects the following functions to be defined
-
-  setsrc(&s);         Set source string pointer and initialize index
-
-along with the zero page variable pairs
+the zero page variable pair
   
-  strlo, strhi        Source String Pointer 
+  ptrlo, ptrhi        System Pointer 
 
-as well as the transient variable 
+and the transient variable 
 
   temp0               Temporary storage
-
diff --git a/include/pointer.a02 b/include/pointer.a02
index 88df46f..3499f10 100644
--- a/include/pointer.a02
+++ b/include/pointer.a02
@@ -1,5 +1,5 @@
 ;C02 library pointer.h02 assembly language subroutines
-;Requires External Zero Page Variables PTRLO, PTRHI, SRCLO, SRCHI
+;Requires External Zero Page Variables PTRLO, PTRHI
 ;External Routines MSETSRC
 
 ;ptrset(&a) - Set Pointer Address
@@ -86,26 +86,3 @@ PTRSUB: STA TEMP0      ;Save Offset
         BCS PTRRET     ;If Borrow
         DEC PTRHI      ;  Decrement High Byte
         RTS
-
-;ptrsav(&a) - Save Pointer Address
-;Args: X,Y = Address of Array to Save Pointer in
-;Sets: SRCLO, SRCHI = Address of Array
-PTRSAV: JSR SETSRC      ;Save Address & Initialize Y Index 
-        LDA PTRLO       ;Get Pointer Low Byte
-        STA (SRCLO),Y   ;Store In First Byte of Array\
-        INY             ;Increment Index
-        LDA PTRHI       ;Get Pointer High Byte
-        STA (SRCLO),Y   ;Store In Second Byte of Array 
-        RTS
-
-;ptrrst(&a) - Restore Pointer Address
-;Args: X,Y = Address of Array to Restore Address
-;Sets: SRCLO, SRCHI = Address of Array
-;      PTRLO, PRTHI = Pointer Value Stores in Array
-PTRRST: JSR SETSRC      ;Save Address & Initialize Y Index 
-        LDA (SRCLO),Y   ;Get First Byte of Array
-        STA PTRLO       ;Store in Pointer Low Byte
-        INY             ;Increment Index
-        LDA (SRCLO),Y   ;Get Second Byte of Array 
-        STA PTRHI       ;Store in Pointer High Byte
-        RTS
diff --git a/include/pointer.h02 b/include/pointer.h02
index ef34d89..e6ae729 100644
--- a/include/pointer.h02
+++ b/include/pointer.h02
@@ -37,11 +37,3 @@ void ptrsub();
  *           0 = Pointer = Address       *
  *           1 = Pointer > Address       */
 void ptrcmp();
-
-/* Save Pointer Value                    *
- * Args: &a - Address to save pointer to */
-void ptrsav();
-
-/* Restore Pointer Value                      *
- * Args: &a - Address to restore pointer from */
-void ptrrst();
diff --git a/vic20/pointers.c02 b/vic20/pointers.c02
index 34eace7..97ea425 100644
--- a/vic20/pointers.c02
+++ b/vic20/pointers.c02
@@ -6,7 +6,8 @@
 #include <stdio.h02>
 #include <pointer.h02>
 
-char psave[2]; //Pointer Storage Variable
+char savelo, savehi; //Pointer Storage Variable
+char ptemp;  //Memory Marker for Compare 
 
 main:
   //Set Pointer to Cassette Buffer
@@ -21,8 +22,8 @@ main:
   prbyte(ptrcmp(&temp0)); newlin();
   outstr(" TBFFR $");
   prbyte(ptrcmp(&tbffr)); newlin();
-  outstr(" PSAVE $");
-  prbyte(ptrcmp(&psave)); newlin();
+  outstr(" PTEMP $");
+  prbyte(ptrcmp(&ptemp)); newlin();
   newlin();
   
   anykey();
@@ -55,15 +56,13 @@ main:
   anykey();
   
   //Demonstrate Save and Restore
-  putstr("SAVE POINTER TO PSAVE");
-  ptrsav(&psave);
-  outstr(" PSAVE IS NOW ");
-  prbyte(psave[1]); prbyte(psave[0]); newlin();
+  putstr("SAVE POINTER");
+  savelo = ptrlo; savehi = ptrhi;
   putstr("CLEAR POINTER");
   ptrlo = 0; ptrhi = 0;
   prpntr();
   putstr("RESTORE FROM PSAVE");
-  ptrrst(&psave);
+  ptrlo = savelo; ptrhi = savehi;
   prpntr();
   
   goto exit;