Add CHAIN command. For #8

Also reworks the general run/load logic a bit.

Author: inexorabletash

README.md

@@ -7,6 +7,7 @@ This is a version of Steve Wozniak's Integer BASIC for the Apple II, with a wrap
    * `SAVE path` saves the current program as an `INT` program file.
    * `LOAD path` loads an `INT` program file.
    * `RUN path` loads and runs an `INT` program file.
+   * `CHAIN path` loads and runs an `INT` program file, without clearing variables.
    * `PREFIX` shows the current ProDOS prefix.
    * `PREFIX path` sets the current ProDOS prefix.
    * `CAT` or `CATALOG` shows the contents of the current directory.

intbasic.system.s

@@ -199,11 +199,9 @@ done_banner:
         bmi     done_path
 
         lda     #OPC_JMP_abs
-        LDXY    #reloc__QuitCmd
+        LDXY    #reloc__QuitFromIntBASIC
         sta     reloc + (intbasic__WARM      - BASIC_START)
         STXY    reloc + (intbasic__WARM+1    - BASIC_START)
-        sta     reloc + (intbasic__ERRMESS   - BASIC_START)
-        STXY    reloc + (intbasic__ERRMESS+1 - BASIC_START)
 
 done_path:
 
@@ -270,40 +268,30 @@ done_path:
 ;;; Load program (if given) and invoke Integer BASIC
 
 .proc Initialize
-        ;; Do we have a path?
-        lda     PATHBUF
-        bne     have_path
-
-        ;; No, just show with prompt
-        jsr     ColdStart
         jsr     SwapZP          ; ProDOS > IntBASIC
-        jmp     intbasic::WARM
-
-        ;; --------------------------------------------------
-        ;; Have path
+        jsr     intbasic::COLD
+        LDXY    #OUR_HIMEM
+        STXY    intbasic::HIMEM
+        jsr     intbasic::NEW   ; reset PP, PV, stacks
+        jsr     SwapZP          ; IntBASIC > ProDOS
 
-have_path:
+        ;; Do we have a path?
+        lda     PATHBUF
+        beq     warm
         jsr     LoadINTFile
-        bne     quit
+        bne     warm
+
+        ;; Run it
         jsr     SwapZP          ; ProDOS > IntBASIC
         jmp     intbasic::RUN
 
-quit:   jmp     QuitCmd         ; fail - just QUIT back to ProDOS
+        ;; Show prompt
+warm:   jsr     SwapZP          ; ProDOS > IntBASIC
+        jmp     intbasic::WARM
 .endproc ; Initialize
 
 ;;; ============================================================
 
-.proc ColdStart
-        jsr     SwapZP          ; ProDOS > IntBASIC
-        jsr     intbasic::COLD
-        LDXY    #OUR_HIMEM
-        STXY    intbasic::HIMEM
-        jsr     intbasic::NEW   ; reset PP, PV, stacks
-        jmp     SwapZP          ; IntBASIC > ProDOS
-.endproc ; ColdStart
-
-;;; ============================================================
-
 ;;; Input: Path to load in `PATHBUF`
 ;;; Output: ProDOS error code in A ($00 = success)
 ;;; Assert: ProDOS ZP swapped in
@@ -332,8 +320,9 @@ open:
         ;; In theory we should check geteof_eof+2 and fail
         ;; if > 64k, but how would such a file be created?
 
-        ;; At this point we're committed - reset HIMEM etc.
-        jsr     ColdStart
+        ;; At this point we're committed - reset HIMEM
+        LDXY    #OUR_HIMEM
+        STXY    intbasic::HIMEM
 
         ;; Set up zero page locations for the calculation
         jsr     SwapZP          ; ProDOS > IntBASIC
@@ -670,7 +659,7 @@ dispatch:
 syn:    ldy     #<intbasic::ErrMsg02 ;"SYNTAX"
         jmp     intbasic::ERRMESS
 
-NUM_CMDS = 17
+NUM_CMDS = 18
 
 cmdtable:
         scrcode "RUN"           ; must be 0 for special handling
@@ -681,6 +670,8 @@ cmdtable:
         .byte   0
         scrcode "LOAD"
         .byte   0
+        scrcode "CHAIN"
+        .byte   0
         scrcode "PREFIX"
         .byte   0
         scrcode "CATALOG"       ; must precede "CAT"
@@ -712,16 +703,17 @@ cmdtable:
         MonCmd := 0             ; ignored
         NomonCmd := 0
 cmdproclo:
-        .byte   <RunCmd,<QuitCmd,<SaveCmd,<LoadCmd,<PrefixCmd,<CatCmd,<CatCmd,<DeleteCmd,<RenameCmd,<BSaveCmd,<BLoadCmd,<BRunCmd,<PRCmd,<MonCmd,<NomonCmd,<LockCmd,<UnlockCmd
+        .byte   <RunCmd,<QuitCmd,<SaveCmd,<LoadCmd,<ChainCmd,<PrefixCmd,<CatCmd,<CatCmd,<DeleteCmd,<RenameCmd,<BSaveCmd,<BLoadCmd,<BRunCmd,<PRCmd,<MonCmd,<NomonCmd,<LockCmd,<UnlockCmd
 cmdprochi:
-        .byte   >RunCmd,>QuitCmd,>SaveCmd,>LoadCmd,>PrefixCmd,>CatCmd,>CatCmd,>DeleteCmd,>RenameCmd,>BSaveCmd,>BLoadCmd,>BRunCmd,>PRCmd,>MonCmd,>NomonCmd,>LockCmd,>UnlockCmd
+        .byte   >RunCmd,>QuitCmd,>SaveCmd,>LoadCmd,>ChainCmd,>PrefixCmd,>CatCmd,>CatCmd,>DeleteCmd,>RenameCmd,>BSaveCmd,>BLoadCmd,>BRunCmd,>PRCmd,>MonCmd,>NomonCmd,>LockCmd,>UnlockCmd
         .assert * - cmdproclo = NUM_CMDS * 2, error, "table size"
 
 cmdparse:
         .byte   ParseFlags::path | ParseFlags::path_opt ; RUN
         .byte   0                                       ; BYE
         .byte   ParseFlags::path                        ; SAVE
         .byte   ParseFlags::path                        ; LOAD
+        .byte   ParseFlags::path                        ; CHAIN
         .byte   ParseFlags::path | ParseFlags::path_opt ; PREFIX
         .byte   ParseFlags::path | ParseFlags::path_opt ; CATALOG
         .byte   ParseFlags::path | ParseFlags::path_opt ; CAT
@@ -1053,6 +1045,11 @@ seen_params:
 ;;; ============================================================
 ;;; "BYE"
 
+.proc QuitFromIntBASIC
+        jsr     SwapZP          ; IntBASIC > ProDOS
+        .assert * = QuitCmd, error, "fall through"
+.endproc
+
 .proc QuitCmd
         MLI_CALL QUIT, quit_params
         brk
@@ -1101,6 +1098,19 @@ seen_params:
 ret:    rts
 .endproc ; LoadCmd
 
+;;; ============================================================
+;;; "CHAIN pathname"
+
+.proc ChainCmd
+        jsr     LoadINTFile
+        bne     ret
+
+        jsr     SwapZP          ; ProDOS > IntBASIC
+        jmp     intbasic::RUNWARM
+
+ret:    rts
+.endproc ; LoadCmd
+
 ;;; ============================================================
 ;;; "RUN pathname"
 
@@ -1109,6 +1119,8 @@ ret:    rts
         bne     LoadCmd::ret
 
         jsr     SwapZP          ; ProDOS > IntBASIC
+        LDXY    intbasic::LOMEM ; reset vars
+        STXY    intbasic::PV
         jmp     intbasic::RUN
 .endproc ; RunCmd
 
@@ -1635,12 +1647,11 @@ output_state:
 
         ;; Exports
         reloc__Initialize := reloc::Initialize
-        reloc__QuitCmd := reloc::QuitCmd
+        reloc__QuitFromIntBASIC := reloc::QuitFromIntBASIC
         reloc__CommandHook := reloc::CommandHook
         reloc__HookCSW := reloc::HookCSW
         intbasic__GETCMD := reloc::intbasic::GETCMD
         intbasic__WARM := reloc::intbasic::WARM
-        intbasic__ERRMESS := reloc::intbasic::ERRMESS
 
         .assert * <= MLI, error, "collision"
         .out .sprintf("MEM: $%04X end of Command Handler", *)

package.sh

@@ -37,7 +37,7 @@ package () {
     add_file "out/intbasic.system.SYS" "IntBASIC.system#FF0000"
     add_file "res/PRODOS.SYS" "PRODOS#FF0000"
     add_file "res/WOZ.BREAKOUT.INT" "WOZ.BREAKOUT#FA0000"
-    add_file "res/TESTS.INT" "TESTS#FA0000"
+    add_file "res/APPLEVISION.INT" "APPLEVISION#FA0000"
     add_file "out/readme" "README#040000"
 
     rm -r "$PACKDIR"

res/APPLEVISION.INT

@@ -2,13 +2,9 @@ Files in this directory are included in disk images.
 
 * `PRODOS.SYS` - from ProDOS 2.4.2 (https://prodos8.com/)
 * `WOZ.BREAKOUT.INT` - is the original published version
-* `TESTS.INT` - integration tests; the source is in `tests.txt`. To update:
+* `tests.txt` - integration tests. To run:
    * `make && make package`
    * `pbcopy < res/tests.txt`
    * Launch Virtual ][
    * mount `out/intbasic_system.2mg` & boot it
    * Paste at the `>` prompt
-   * `SAVE TESTS`
-   * Quit Virtual ][
-   * `cadius EXTRACTFILE out/intbasic_system.2mg /INTBASIC/TESTS res`
-   * `mv res/TESTS#FA0000 res/TESTS.INT`