Checkpoint

src/blitter/Scanline.s

@@ -169,4 +169,37 @@ _ScanlineBG0XPos
                     cmp   :last_line_x2
                     jne   :loop
 
-                    rts
+                    rts
+
+; Unrolled copy routine to move BankTable entries into BNK_ADDR position.  This is a bit different than the
+; other routines, because we don't need to put values into the code fields, but just copy one-byte values
+; into an internal array in bank 00 space.  The reason for this is because the code sequence
+;
+; lda #ADDR
+; tcs
+; plb
+;
+; Take only 9 cycles, but the alternative is slower
+;
+; pea #$BBBB
+; plb
+; plb         = 13 cycles
+;
+; If for some reason it becimes important to preserve the accumulator, or save the 208 bytes of
+; bank 00 memory, then we can change it.  The advantage right now is that updating the array can
+; be done 16-bits at a time and without having to chunk up the writes across multiple banks.  This
+; is quite a bit faster than the other routines.
+CopyTableToBankBytes
+
+                     tsx                             ; save the stack
+                     sei
+                     jmp   $0000
+
+                     lda:  2,y
+                     pha
+                     lda:  0,y
+                     pha
+bottom
+                     txs                             ; restore the stack
+                     cli                             ; turn interrupts back on
+                     rts

src/blitter/Template.s

@@ -5,10 +5,12 @@
 DP_ADDR            equ   entry_1-base+1             ; offset to patch in the direct page for dynamic tiles
 BG1_ADDR           equ   entry_2-base+1             ; offset to patch in the Y-reg for BG1 (dp),y addressing
 STK_ADDR           equ   entry_3-base+1             ; offset to patch in the stack (SHR) right edge address
+BNK_ADDR           equ   entry_0-base+1             ; offset to patch in the address of a Bank 0 memory location to load the bank register
 
 DP_ENTRY           equ   entry_1-base
 TWO_LYR_ENTRY      equ   entry_2-base
 ONE_LYR_ENTRY      equ   entry_3-base
+BANK_ENTRY         equ   entry_0-base
 
 CODE_ENTRY_OPCODE  equ   entry_jmp-base
 CODE_ENTRY         equ   entry_jmp-base+1           ; low byte of the page-aligned jump address
@@ -66,6 +68,9 @@ BankPatchNum       equ   *-BankPatches
 ; the code is assembled on a page boundary to help with alignment
                    ds    \,$00                      ; pad to the next page boundary
 base
+entry_0            lda   #0000                      ; Used to set per-scanline bank register
+                   tcs
+                   plb
 entry_1            ldx   #0000                      ; Used for LDA 00,x addressing (Dynamic Tiles)
 entry_2            ldy   #0000                      ; Used for LDA (00),y addressing (Second Layer; BG1)
 entry_3            lda   #0000                      ; Sets screen address (right edge)

src/blitter/TemplateUtils.s

@@ -245,8 +245,8 @@ BuildBank
                    plb
                    plb
 
-; Change the patched value to one of DP_ENTRY, TWO_LYR_ENTRY or ONE_LYR_ENTRY based on the capabilities
-; that the engine needs.
+; Change the patched value to one of BANK_ENTRY, DP_ENTRY, TWO_LYR_ENTRY or ONE_LYR_ENTRY based
+; on the capabilities that the engine needs.
 
                    lda   #DP_ENTRY
                    sta   :entryOffset