C128 port groundwork: make module zero page target-selectable

editor.asm

@@ -142,11 +142,18 @@ CLR_PTR:      .res 2        ; color RAM row pointer
 CLR_KWLEN:    .res 1        ; keyword length returned by col_try_keyword
 CLR_CTMP:     .res 2        ; colortab walk pointer (col_try_keyword internal)
 
-; col_try_keyword uses ZP scratch at $3A for the matched token byte.
-; This byte is above the editor's reserved ZP block ($02-$1B) and is
-; the same address used by modtok.asm — safe to alias here since the
+; col_try_keyword needs one byte of scratch for the matched token byte.
+; It borrows the first byte of the *module* scratch pool rather than
+; spending one of the editor's own reserved bytes — safe only because the
 ; editor never calls tokenizer code directly.
-KW_TOKEN      = $3A          ; token byte from col_try_keyword (colorize scratch)
+;
+; This is the one place the editor reaches across into module zero page, so
+; it must track any relocation of that pool: hence zp.inc rather than a
+; literal. See docs/c128-port-notes.md ("Cross-tier alias") — the intent is
+; to retire this alias once the C128 map puts both tiers in one region.
+.include "zp.inc"
+
+KW_TOKEN      = ZP_SCRATCH+0 ; token byte from col_try_keyword (colorize scratch)
 
 
 .segment "LOADADDR"

modasm.asm

@@ -87,10 +87,13 @@ COLS        = 40
 DEFAULT_COLOR = 14          ; light blue
 
 ; ---- ZP ----
-SRC_PTR  = $FB   ; lo (hi=$FC)  -  source walker, gap-aware
-TMP      = $3A   ; general scratch (hi=$3B)
-TMP2     = $3C   ; (hi=$3D)
-TMP3     = $3E   ; (hi=$3F)
+; Addresses come from zp.inc (see docs/c128-port-notes.md).
+.include "zp.inc"
+
+SRC_PTR  = ZP_PTR2       ; lo (hi=+1)  -  source walker, gap-aware
+TMP      = ZP_SCRATCH+0  ; general scratch (hi=+1)
+TMP2     = ZP_SCRATCH+2  ; (hi=+3)
+TMP3     = ZP_SCRATCH+4  ; (hi=+5)
 
 ; ---- Mode constants ----
 MODE_IMP = 0
@@ -127,7 +130,9 @@ ASM_FNAME_LEN   = $C021   ; output filename length
 ASM_FNAME       = $C022   ; output filename (16 bytes)
 
 ; ---- ZP save area ----
-ZP_SAVE         = $C03A   ; 10 bytes: saves $3A-$3F, $FB-$FE
+; 10 bytes: saves the 6-byte ZP_SCRATCH block plus ZP_PTR2/ZP_PTR3.
+; (Not zero page itself — module scratch RAM above the $A000 image.)
+ZP_SAVE         = $C03A
 
 ; ---- Gap pointers (copied from params) ----
 ASM_GAP_S_LO    = $C032
@@ -276,18 +281,18 @@ assemble:
     ; Save ZP
     ldx #0
 @zpsave:
-    lda $3A,x
+    lda ZP_SCRATCH,x
     sta ZP_SAVE,x
     inx
-    cpx #6
+    cpx #ZP_SCRATCH_LEN
     bne @zpsave
-    lda $FB
+    lda ZP_PTR2
     sta ZP_SAVE+6
-    lda $FC
+    lda ZP_PTR2+1
     sta ZP_SAVE+7
-    lda $FD
+    lda ZP_PTR3
     sta ZP_SAVE+8
-    lda $FE
+    lda ZP_PTR3+1
     sta ZP_SAVE+9
 
     ; Copy gap/buffer params
@@ -453,18 +458,18 @@ assemble:
     ldx #0
 @zprest:
     lda ZP_SAVE,x
-    sta $3A,x
+    sta ZP_SCRATCH,x
     inx
-    cpx #6
+    cpx #ZP_SCRATCH_LEN
     bne @zprest
     lda ZP_SAVE+6
-    sta $FB
+    sta ZP_PTR2
     lda ZP_SAVE+7
-    sta $FC
+    sta ZP_PTR2+1
     lda ZP_SAVE+8
-    sta $FD
+    sta ZP_PTR3
     lda ZP_SAVE+9
-    sta $FE
+    sta ZP_PTR3+1
     cli                         ; re-enable IRQ before returning
     rts
 

moddet.asm

@@ -60,14 +60,17 @@ MOD_NEW_END_HI   = $0220
 MOD_MAGIC_VAL    = $4D
 
 ; ---- Zero page -------------------------------------------------------------
-SRC_PTR          = $FB              ; source walk pointer (lo/hi)
-DST_PTR          = $FD              ; output write pointer (lo/hi)
-COPY_SRC         = $F7              ; copy-back source (lo/hi)
-COPY_DST         = $F9              ; copy-back dest  (lo/hi)
-LINENO           = $3A              ; 16-bit line number scratch (lo/hi)
-NZFLAG           = $3C              ; non-zero digit seen (decimal output)
-KWTAB            = $3D              ; keyword table walker (lo/hi)
-OVFLAG           = $3F              ; output-overflow flag ($FF = won't fit)
+; Addresses come from zp.inc (see docs/c128-port-notes.md).
+.include "zp.inc"
+
+SRC_PTR          = ZP_PTR2          ; source walk pointer (lo/hi)
+DST_PTR          = ZP_PTR3          ; output write pointer (lo/hi)
+COPY_SRC         = ZP_PTR0          ; copy-back source (lo/hi)
+COPY_DST         = ZP_PTR1          ; copy-back dest  (lo/hi)
+LINENO           = ZP_SCRATCH+0     ; 16-bit line number scratch (lo/hi)
+NZFLAG           = ZP_SCRATCH+2     ; non-zero digit seen (decimal output)
+KWTAB            = ZP_SCRATCH+3     ; keyword table walker (lo/hi)
+OVFLAG           = ZP_SCRATCH+5     ; output-overflow flag ($FF = won't fit)
 
 
 

moddis.asm

@@ -67,11 +67,14 @@ MOD_NEW_END_HI   = $0220
 CHROUT           = $FFD2
 
 ; ---- ZP ----
-SRC_PTR          = $FB          ; lo (hi=$FC) - source walker
-DST_PTR          = $FD          ; output pointer lo (hi at $FE); consecutive pair for (addr),y
-TMP              = $3A          ; scratch (hi=$3B)
-TMP2             = $3C          ; scratch (hi=$3D)
-TMP3             = $3E          ; scratch (hi=$3F)
+; Addresses come from zp.inc (see docs/c128-port-notes.md).
+.include "zp.inc"
+
+SRC_PTR          = ZP_PTR2      ; lo (hi=+1) - source walker
+DST_PTR          = ZP_PTR3      ; output pointer lo (hi at +1); consecutive pair for (addr),y
+TMP              = ZP_SCRATCH+0 ; scratch (hi=+1)
+TMP2             = ZP_SCRATCH+2 ; scratch (hi=+3)
+TMP3             = ZP_SCRATCH+4 ; scratch (hi=+5)
 
 ; ---- ZP save area and disassembler state ----
 ; Declared at the end of this file (after all code/tables) as plain labels
@@ -128,18 +131,18 @@ disassemble:
     ; Save ZP
     ldx #0
 @zpsave:
-    lda $3A,x
+    lda ZP_SCRATCH,x
     sta ZP_SAVE,x
     inx
-    cpx #6
+    cpx #ZP_SCRATCH_LEN
     bne @zpsave
-    lda $FB
+    lda ZP_PTR2
     sta ZP_SAVE+6
-    lda $FC
+    lda ZP_PTR2+1
     sta ZP_SAVE+7
-    lda $FD
+    lda ZP_PTR3
     sta ZP_SAVE+8
-    lda $FE
+    lda ZP_PTR3+1
     sta ZP_SAVE+9
 
     ; Copy params
@@ -321,18 +324,18 @@ disassemble:
     ldx #0
 @zprestore:
     lda ZP_SAVE,x
-    sta $3A,x
+    sta ZP_SCRATCH,x
     inx
-    cpx #6
+    cpx #ZP_SCRATCH_LEN
     bne @zprestore
     lda ZP_SAVE+6
-    sta $FB
+    sta ZP_PTR2
     lda ZP_SAVE+7
-    sta $FC
+    sta ZP_PTR2+1
     lda ZP_SAVE+8
-    sta $FD
+    sta ZP_PTR3
     lda ZP_SAVE+9
-    sta $FE
+    sta ZP_PTR3+1
 
     ; Report success
     lda #$02
@@ -1122,7 +1125,7 @@ mnem_strs:
 ; TXS/TYA corruption bug this file used to have.
 ; ============================================================================
 
-ZP_SAVE:          .res 10         ; saves $3A-$3F, $FB-$FE
+ZP_SAVE:          .res 10         ; saves ZP_SCRATCH (6) + ZP_PTR2/ZP_PTR3 (4)
 DIS_PC_LO:        .res 1          ; current PC lo
 DIS_PC_HI:        .res 1          ; current PC hi
 DIS_SRC_END_LO:   .res 1          ; end of source binary lo (= GAP_START)

moddsk.asm

@@ -167,7 +167,7 @@ DSK_FREE_LO:     .res 1     ; blocks free lo
 DSK_FREE_HI:     .res 1     ; blocks free hi
 DSK_DISKNAME:    .res 16    ; disk name, 16 bytes PETSCII
 DSK_DISKID:      .res 2     ; disk id, 2 bytes
-DSK_ZP_SAVE:     .res 4     ; saved ZP $FB-$FE
+DSK_ZP_SAVE:     .res 4     ; saved ZP_PTR2 / ZP_PTR3
 DSK_TMP:         .res 1     ; general scratch byte
 DSK_TMP2:        .res 1     ; second scratch byte
 DSK_NAMELEN_TMP: .res 1     ; scratch for rename/format input length
@@ -186,8 +186,11 @@ DSK_CACHE:       .res 680   ; directory cache: 34 entries × 20 bytes
 ; throughout the code will resolve correctly via the linker.
 
 ; Zero page pointers (saved/restored)
-DSK_PTR         = $FB       ; lo (hi = $FC)
-DSK_PTR2        = $FD       ; lo (hi = $FE)
+; Addresses come from zp.inc (see docs/c128-port-notes.md).
+.include "zp.inc"
+
+DSK_PTR         = ZP_PTR2   ; lo (hi = +1)
+DSK_PTR2        = ZP_PTR3   ; lo (hi = +1)
 
 ; ============================================================================
 ; Module entry point
@@ -215,13 +218,13 @@ disk_main:
     sta $01
 
     ; Save ZP
-    lda $FB
+    lda ZP_PTR2
     sta DSK_ZP_SAVE+0
-    lda $FC
+    lda ZP_PTR2+1
     sta DSK_ZP_SAVE+1
-    lda $FD
+    lda ZP_PTR3
     sta DSK_ZP_SAVE+2
-    lda $FE
+    lda ZP_PTR3+1
     sta DSK_ZP_SAVE+3
 
     ; Copy drive from parameter block
@@ -328,13 +331,13 @@ disk_main:
 dsk_exit:
     ; Restore ZP
     lda DSK_ZP_SAVE+0
-    sta $FB
+    sta ZP_PTR2
     lda DSK_ZP_SAVE+1
-    sta $FC
+    sta ZP_PTR2+1
     lda DSK_ZP_SAVE+2
-    sta $FD
+    sta ZP_PTR3
     lda DSK_ZP_SAVE+3
-    sta $FE
+    sta ZP_PTR3+1
     rts
 
 ; ============================================================================

modren.asm

@@ -53,11 +53,14 @@ SPIN_COLOR_A     = $01
 SPIN_COLOR_B     = $00
 
 ; ---- Zero page (saved / restored around module call) ----
-SRC_PTR          = $FB          ; 16-bit source walker    ($FC = hi)
-DST_PTR          = $FD          ; 16-bit destination ptr  ($FE = hi)
-TMP              = $3A          ; scratch lo              ($3B = hi)
-TMP2             = $3C          ; number lo               ($3D = TMP2+1 = hi)
-TMP3             = $3E          ; table ptr lo            ($3F = TMP3+1 = hi)
+; Addresses come from zp.inc (see docs/c128-port-notes.md).
+.include "zp.inc"
+
+SRC_PTR          = ZP_PTR2      ; 16-bit source walker    (+1 = hi)
+DST_PTR          = ZP_PTR3      ; 16-bit destination ptr  (+1 = hi)
+TMP              = ZP_SCRATCH+0 ; scratch lo              (+1 = hi)
+TMP2             = ZP_SCRATCH+2 ; number lo               (TMP2+1 = hi)
+TMP3             = ZP_SCRATCH+4 ; table ptr lo            (TMP3+1 = hi)
 
 ; ============================================================================
 .segment "LOADADDR"
@@ -78,22 +81,22 @@ modren_entry:
     cli
     rts
 :
-    ; Save ZP $3A-$3F
+    ; Save the ZP_SCRATCH block
     ldx #0
 @zpsave:
-    lda $3A,x
+    lda ZP_SCRATCH,x
     sta ZP_SAVE,x
     inx
-    cpx #6
+    cpx #ZP_SCRATCH_LEN
     bne @zpsave
-    ; Save $FB-$FE
-    lda $FB
+    ; Save ZP_PTR2 / ZP_PTR3
+    lda ZP_PTR2
     sta ZP_SAVE+6
-    lda $FC
+    lda ZP_PTR2+1
     sta ZP_SAVE+7
-    lda $FD
+    lda ZP_PTR3
     sta ZP_SAVE+8
-    lda $FE
+    lda ZP_PTR3+1
     sta ZP_SAVE+9
 
     ; Copy MOD parameters into local state
@@ -164,18 +167,18 @@ modren_entry:
     ldx #0
 @zprestore:
     lda ZP_SAVE,x
-    sta $3A,x
+    sta ZP_SCRATCH,x
     inx
-    cpx #6
+    cpx #ZP_SCRATCH_LEN
     bne @zprestore
     lda ZP_SAVE+6
-    sta $FB
+    sta ZP_PTR2
     lda ZP_SAVE+7
-    sta $FC
+    sta ZP_PTR2+1
     lda ZP_SAVE+8
-    sta $FD
+    sta ZP_PTR3
     lda ZP_SAVE+9
-    sta $FE
+    sta ZP_PTR3+1
 
     cli
     rts

modscr.asm

@@ -90,7 +90,12 @@ IDE_LEN_LO = <($9FFF - $0801 + 1)
 IDE_LEN_HI = >($9FFF - $0801 + 1)
 
 ; ---- Scratch ----
-TMP16      = $3C      ; lo (hi=$3D)
+; Address comes from zp.inc (see docs/c128-port-notes.md). The BASIC ABI
+; locations above (TXTTAB, VARTAB, MEMSIZ) are fixed by the ROM and are
+; deliberately NOT part of the relocatable pool.
+.include "zp.inc"
+
+TMP16      = ZP_SCRATCH+2  ; lo (hi=+3)
 
 ; Metadata fetch buffer (module RAM, reused after verify)
 META_BUF   = $B000

modscrh.asm

@@ -137,8 +137,13 @@ VEC_IERROR  = $0300
 VEC_IMAIN   = $0302
 VEC_IGONE   = $0308
 
-; ZP scratch
-HND_TMP     = $3C     ; lo (hi=$3D) — scratch pointer (no conflict during script)
+; ZP scratch — address comes from zp.inc (see docs/c128-port-notes.md).
+; NOTE: the BASIC ABI locations this module also uses (TXTTAB, VARTAB,
+; VARPNT, BASIC_TXTPTR, and AYINT's $14/$15 output) are fixed by the ROM and
+; are deliberately NOT part of the relocatable pool.
+.include "zp.inc"
+
+HND_TMP     = ZP_SCRATCH+2  ; lo (hi=+3) — scratch pointer (no conflict during script)
 
 ; Module status
 MOD_STATUS  = $021E