;;; $CB8E: X-ray setup stage 4 - build x-ray BG2 tilemap, read BG2 tilemap - 1st screen ;;;
{
; Calls $84:831A to load item x-ray blocks
$91:CB8E 08          PHP
$91:CB8F C2 30       REP #$30
$91:CB91 AD 1F 09    LDA $091F  [$7E:091F]  ;\
$91:CB94 18          CLC                    ;|
$91:CB95 6D 15 09    ADC $0915  [$7E:0915]  ;|
$91:CB98 29 F0 00    AND #$00F0             ;|
$91:CB9B 0A          ASL A                  ;|
$91:CB9C 0A          ASL A                  ;|
$91:CB9D 85 18       STA $18    [$7E:0018]  ;|
$91:CB9F AD 1D 09    LDA $091D  [$7E:091D]  ;|
$91:CBA2 18          CLC                    ;|
$91:CBA3 6D 11 09    ADC $0911  [$7E:0911]  ;|
$91:CBA6 29 F0 00    AND #$00F0             ;|
$91:CBA9 4A          LSR A                  ;} $18 (BG1 row origin block index) =
$91:CBAA 4A          LSR A                  ;}       (([BG1 Y offset] + [layer 1 Y position]) / 8 & 1Eh) * 20h (20h tiles per tilemap row, rounded down to top-left of 16x16 block)
$91:CBAB 4A          LSR A                  ;}     + (([BG1 X offset] + [layer 1 X position]) / 8 & 1Eh)       (1 byte per tilemap column, rounded down to top-left of 16x16 block)
$91:CBAC 18          CLC                    ;}     + ([BG1 X offset] + [layer 1 X position]) / 100h % 2 * 400h (400h tiles per tilemap screen)
$91:CBAD 65 18       ADC $18    [$7E:0018]  ;|
$91:CBAF 85 18       STA $18    [$7E:0018]  ;|
$91:CBB1 AD 1D 09    LDA $091D  [$7E:091D]  ;|
$91:CBB4 18          CLC                    ;|
$91:CBB5 6D 11 09    ADC $0911  [$7E:0911]  ;|
$91:CBB8 29 00 01    AND #$0100             ;|
$91:CBBB 0A          ASL A                  ;|
$91:CBBC 0A          ASL A                  ;|
$91:CBBD 18          CLC                    ;|
$91:CBBE 65 18       ADC $18    [$7E:0018]  ;|
$91:CBC0 85 18       STA $18    [$7E:0018]  ;/
$91:CBC2 64 16       STZ $16    [$7E:0016]  ; $16 = 0 (x-ray BG2 tilemap index)
$91:CBC4 A9 10 00    LDA #$0010             ;\
$91:CBC7 85 14       STA $14    [$7E:0014]  ;} $14 = 10h (row loop counter)
; LOOP_COPY_BG1_ROW
$91:CBC9 A9 10 00    LDA #$0010             ;\
$91:CBCC 85 12       STA $12    [$7E:0012]  ;} $12 = 10h (column loop counter)
$91:CBCE A5 18       LDA $18    [$7E:0018]  ;\
$91:CBD0 29 E0 07    AND #$07E0             ;} $1A = [BG1 row origin block index] & 7E0h (BG1 row origin block row index)
$91:CBD3 85 1A       STA $1A    [$7E:001A]  ;/
$91:CBD5 A5 18       LDA $18    [$7E:0018]  ;\
$91:CBD7 29 1F 00    AND #$001F             ;} $1C = [BG1 row origin block index] & 1Fh (BG1 row origin block column index)
$91:CBDA 85 1C       STA $1C    [$7E:001C]  ;/
$91:CBDC 64 1E       STZ $1E    [$7E:001E]  ; $1E = 0 (BG1 block X offset)
; LOOP_COPY_BG1_COLUMN
$91:CBDE A5 1C       LDA $1C    [$7E:001C]  ;\
$91:CBE0 18          CLC                    ;|
$91:CBE1 65 1E       ADC $1E    [$7E:001E]  ;} If [BG1 row origin block column index] + [BG1 block X offset] >= 20h (reached end of tilemap screen):
$91:CBE3 C9 20 00    CMP #$0020             ;|
$91:CBE6 30 12       BMI $12    [$CBFA]     ;/
$91:CBE8 A5 1A       LDA $1A    [$7E:001A]  ;\
$91:CBEA 18          CLC                    ;|
$91:CBEB 69 00 04    ADC #$0400             ;} BG1 row origin block row index = [BG1 row origin block row index] + 400h & 7E0h (switch tilemap screens)
$91:CBEE 29 E0 07    AND #$07E0             ;|
$91:CBF1 85 1A       STA $1A    [$7E:001A]  ;/
$91:CBF3 A9 00 00    LDA #$0000             ;\
$91:CBF6 85 1C       STA $1C    [$7E:001C]  ;} BG1 row origin block column index = 0
$91:CBF8 85 1E       STA $1E    [$7E:001E]  ; BG1 block X offset = 0
$91:CBFA A5 1A       LDA $1A    [$7E:001A]  ;\
$91:CBFC 18          CLC                    ;|
$91:CBFD 65 1C       ADC $1C    [$7E:001C]  ;|
$91:CBFF 65 1E       ADC $1E    [$7E:001E]  ;} X = ([BG1 row origin block row index] + [BG1 row origin block column index] + [BG1 block X offset]) * 2
$91:CC01 0A          ASL A                  ;|
$91:CC02 AA          TAX                    ;/
$91:CC03 BF 00 60 7E LDA $7E6000,x[$7E:650C];\
$91:CC07 48          PHA                    ;} $7E:4000 + [x-ray BG2 tilemap index] = [$7E:6000 + [X]]
$91:CC08 BF 02 60 7E LDA $7E6002,x[$7E:650E]; \
$91:CC0C 48          PHA                    ; } $7E:4000 + [x-ray BG2 tilemap index] + 2 = [$7E:6000 + [X] + 2]
$91:CC0D BF 40 60 7E LDA $7E6040,x[$7E:654C];  \
$91:CC11 48          PHA                    ;  } $7E:4000 + [x-ray BG2 tilemap index] + 40h = [$7E:6000 + [X] + 40h]
$91:CC12 BF 42 60 7E LDA $7E6042,x[$7E:654E];   \
$91:CC16 A6 16       LDX $16    [$7E:0016]  ;   } $7E:4000 + [x-ray BG2 tilemap index] + 42h = [$7E:6000 + [X] + 42h]
$91:CC18 9F 42 40 7E STA $7E4042,x[$7E:4042];   /
$91:CC1C 68          PLA                    ;  |
$91:CC1D 9F 40 40 7E STA $7E4040,x[$7E:4040];  /
$91:CC21 68          PLA                    ; |
$91:CC22 9F 02 40 7E STA $7E4002,x[$7E:4002]; /
$91:CC26 68          PLA                    ;|
$91:CC27 9F 00 40 7E STA $7E4000,x[$7E:4000];/
$91:CC2B A5 16       LDA $16    [$7E:0016]  ;\
$91:CC2D 18          CLC                    ;|
$91:CC2E 69 04 00    ADC #$0004             ;} X-ray BG2 tilemap index += 4 (move right two tilemap columns)
$91:CC31 85 16       STA $16    [$7E:0016]  ;/
$91:CC33 A5 1E       LDA $1E    [$7E:001E]  ;\
$91:CC35 69 02 00    ADC #$0002             ;} BG1 block X offset += 2 (move right two tilemap columns)
$91:CC38 85 1E       STA $1E    [$7E:001E]  ;/
$91:CC3A C6 12       DEC $12    [$7E:0012]  ; Decrement $12
$91:CC3C D0 A0       BNE $A0    [$CBDE]     ; If [$12] != 0: go to LOOP_COPY_BG1_COLUMN
$91:CC3E 20 F1 CC    JSR $CCF1  [$91:CCF1]  ; Copy last BG1 block of row to x-ray BG2 tilemap
$91:CC41 A5 18       LDA $18    [$7E:0018]  ;\
$91:CC43 29 00 04    AND #$0400             ;|
$91:CC46 85 20       STA $20    [$7E:0020]  ;|
$91:CC48 A5 18       LDA $18    [$7E:0018]  ;|
$91:CC4A 18          CLC                    ;} BG1 row origin block index = ([BG1 row origin block index] & 400h)
$91:CC4B 69 40 00    ADC #$0040             ;}                            + ([BG1 row origin block index] + 40h & 3FFh) (move down two tilemap rows)
$91:CC4E 29 FF 03    AND #$03FF             ;|
$91:CC51 18          CLC                    ;|
$91:CC52 65 20       ADC $20    [$7E:0020]  ;|
$91:CC54 85 18       STA $18    [$7E:0018]  ;/
$91:CC56 A5 16       LDA $16    [$7E:0016]  ;\
$91:CC58 18          CLC                    ;|
$91:CC59 69 40 00    ADC #$0040             ;} X-ray BG2 tilemap index += 40h (move down two tilemap rows)
$91:CC5C 85 16       STA $16    [$7E:0016]  ;/
$91:CC5E C6 14       DEC $14    [$7E:0014]  ; Decrement $14
$91:CC60 F0 03       BEQ $03    [$CC65]     ; If [$14] != 0:
$91:CC62 4C C9 CB    JMP $CBC9  [$91:CBC9]  ; Go to LOOP_COPY_BG1_ROW
$91:CC65 AD 15 09    LDA $0915  [$7E:0915]  ;\
$91:CC68 4A          LSR A                  ;|
$91:CC69 4A          LSR A                  ;|
$91:CC6A 4A          LSR A                  ;|
$91:CC6B 4A          LSR A                  ;|
$91:CC6C EB          XBA                    ;|
$91:CC6D 0D A5 07    ORA $07A5  [$7E:07A5]  ;|
$91:CC70 8D 02 42    STA $4202              ;|
$91:CC73 AD 11 09    LDA $0911  [$7E:0911]  ;} $22 = [layer 1 Y position] / 10h * [room width in blocks] + [layer 1 X position] / 10h (block index)
$91:CC76 4A          LSR A                  ;|
$91:CC77 4A          LSR A                  ;|
$91:CC78 4A          LSR A                  ;|
$91:CC79 4A          LSR A                  ;|
$91:CC7A 18          CLC                    ;|
$91:CC7B 6D 16 42    ADC $4216              ;|
$91:CC7E 85 22       STA $22    [$7E:0022]  ;/
$91:CC80 64 16       STZ $16    [$7E:0016]  ; $16 = 0 (x-ray BG2 tilemap index)
$91:CC82 A9 10 00    LDA #$0010             ;\
$91:CC85 85 14       STA $14    [$7E:0014]  ;} $14 = 10h (row loop counter)
; LOOP_REVEALED_ROW
$91:CC87 20 42 CD    JSR $CD42  [$91:CD42]  ; Load right half of revealed 2xN block
$91:CC8A A9 10 00    LDA #$0010             ;\
$91:CC8D 85 12       STA $12    [$7E:0012]  ;} $12 = 10h (column loop counter)
$91:CC8F A5 22       LDA $22    [$7E:0022]  ;\
$91:CC91 85 24       STA $24    [$7E:0024]  ;} $24 = (block index)
; LOOP_REVEALED_COLUMN
$91:CC93 20 BE CD    JSR $CDBE  [$91:CDBE]  ; Load revealed block
$91:CC96 C6 12       DEC $12    [$7E:0012]  ; Decrement $12
$91:CC98 D0 F9       BNE $F9    [$CC93]     ; If [$12] != 0: go to LOOP_REVEALED_COLUMN
$91:CC9A A5 16       LDA $16    [$7E:0016]  ;\
$91:CC9C 48          PHA                    ;} A = [$16]
$91:CC9D 18          CLC                    ;\
$91:CC9E 69 C0 07    ADC #$07C0             ;} $16 += 7C0h
$91:CCA1 85 16       STA $16    [$7E:0016]  ;/
$91:CCA3 20 BE CD    JSR $CDBE  [$91:CDBE]  ; Load revealed block
$91:CCA6 68          PLA                    ;\
$91:CCA7 18          CLC                    ;|
$91:CCA8 69 40 00    ADC #$0040             ;} $16 = [A] + 40h
$91:CCAB 85 16       STA $16    [$7E:0016]  ;/
$91:CCAD A5 22       LDA $22    [$7E:0022]  ;\
$91:CCAF 18          CLC                    ;|
$91:CCB0 6D A5 07    ADC $07A5  [$7E:07A5]  ;} (Block index) += [room width]
$91:CCB3 85 22       STA $22    [$7E:0022]  ;/
$91:CCB5 C6 14       DEC $14    [$7E:0014]  ; Decrement $14
$91:CCB7 D0 CE       BNE $CE    [$CC87]     ; If [$14] != 0: go to LOOP_REVEALED_ROW
$91:CCB9 22 1A 83 84 JSL $84831A[$84:831A]  ; Load item x-ray blocks
$91:CCBD AE 60 03    LDX $0360  [$7E:0360]  ;\
$91:CCC0 A5 59       LDA $59    [$7E:0059]  ;|
$91:CCC2 29 FC 00    AND #$00FC             ;|
$91:CCC5 EB          XBA                    ;|
$91:CCC6 9D 40 03    STA $0340,x[$7E:0340]  ;|
$91:CCC9 A9 81 00    LDA #$0081             ;|
$91:CCCC 9D 42 03    STA $0342,x[$7E:0342]  ;|
$91:CCCF A9 39 00    LDA #$0039             ;|
$91:CCD2 9D 43 03    STA $0343,x[$7E:0343]  ;|
$91:CCD5 A9 00 50    LDA #$5000             ;} Queue transfer of 800h bytes from VRAM BG2 tilemap base to $7E:5000
$91:CCD8 9D 44 03    STA $0344,x[$7E:0344]  ;|
$91:CCDB A9 7E 00    LDA #$007E             ;|
$91:CCDE 9D 46 03    STA $0346,x[$7E:0346]  ;|
$91:CCE1 A9 00 08    LDA #$0800             ;|
$91:CCE4 9D 47 03    STA $0347,x[$7E:0347]  ;|
$91:CCE7 8A          TXA                    ;|
$91:CCE8 18          CLC                    ;|
$91:CCE9 69 09 00    ADC #$0009             ;|
$91:CCEC 8D 60 03    STA $0360  [$7E:0360]  ;/
$91:CCEF 28          PLP
$91:CCF0 6B          RTL
}