First public commit.

lenser/atari/viewer/cart.s

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+; lenser -- Atari 16K cartridge loader ($8000-$BFFF).
+;
+; Reuses the disk viewer unchanged.  The disk viewer "stub" (origin $2000, which
+; begins with the 6-byte boot header and contains cont + the display list) and
+; the picture data (origin $4000) are stored back-to-back in the cartridge ROM
+; after this loader.  We copy the stub to $2000 and the data to $4000, then jump
+; to cont ($2006) -- exactly the state a disk boot would have produced.
+;
+; #defines set by viewer/assemble.py --
+;   STUB_PAGES / DATA_PAGES   256-byte page counts to copy
+;   STUB_LEN                  exact stub length (data follows it in ROM)
+;
+; assembled by atari/viewer/assemble.py via xa
+
+        * = $8000
+
+S = $80
+D = $82
+
+entry:
+        ; ---- copy the viewer stub to $2000 ----
+        lda #<stubsrc
+        sta S
+        lda #>stubsrc
+        sta S+1
+        lda #$00
+        sta D
+        lda #$20
+        sta D+1
+        ldx #STUB_PAGES
+        ldy #$00
+sc:
+        lda (S),y
+        sta (D),y
+        iny
+        bne sc
+        inc S+1
+        inc D+1
+        dex
+        bne sc
+
+        ; ---- copy the picture data to $4000 ----
+        lda #<datasrc
+        sta S
+        lda #>datasrc
+        sta S+1
+        lda #$00
+        sta D
+        lda #$40
+        sta D+1
+        ldx #DATA_PAGES
+        ldy #$00
+dc:
+        lda (S),y
+        sta (D),y
+        iny
+        bne dc
+        inc S+1
+        inc D+1
+        dex
+        bne dc
+
+        jmp $2006               ; enter the disk viewer (cont)
+
+stubsrc:
+        ; viewer stub + picture data appended here by the packager
+datasrc = stubsrc + STUB_LEN