git.y1.nz

commit d009bfeeda801a44bea741c794be463782b81956
parent 0c243451c582c0420d674673d05091327327168d
Author: Michel Iwaniec <46843052+michel-iwaniec@users.noreply.github.com>
Date:   Sun, 20 Oct 2024 00:10:49 +0100

NES: Fix bug with multiple column attribute updates (#721)

* Make sure that each column re-adds PPU lo offset instead of storing it
* Wrap functionality in a macro WRITEVERT
Diffstat:
M
gbdk-lib/libc/targets/mos6502/nes/flush_attributes.s
29
+++++++++++++++--------------

1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/gbdk-lib/libc/targets/mos6502/nes/flush_attributes.s b/gbdk-lib/libc/targets/mos6502/nes/flush_attributes.s
@@ -82,29 +82,30 @@ _flush_shadow_attributes_columns_next_column:
 _flush_shadow_attributes_columns_end:
     rts
 
-;
-; Flushes all dirty rows of _attribute_shadow by writing them to PPU memory
-;
-_flush_shadow_attributes_update_column:
-    ; Update all 8 bytes of column for now, as each column in _attribute_column_dirty only stores 1 bit
-    ; As PPU has no increment-by-8 feature, split writes into 4 separate stripes 2 bytes each
-    ; TODO: Could make a dedicated unrolled transfer routine in nmi handler that writes all 8 bytes as one stripe.
-    i = 0
-    .rept 4
+.macro WRITEVERT
     lda *.tmp+1
     tax
     lda *.tmp
+    clc
+    adc #(8*i)
     jsr .ppu_stripe_begin_vertical
     lda _attribute_shadow+8*i,y
     jsr .ppu_stripe_write_byte
     lda _attribute_shadow+8*i+32,y
     jsr .ppu_stripe_write_byte
     jsr .ppu_stripe_end
-    ;
-    lda *.tmp
-    clc
-    adc #8
-    sta *.tmp
+.endm
+
+;
+; Flushes all dirty rows of _attribute_shadow by writing them to PPU memory
+;
+_flush_shadow_attributes_update_column:
+    ; Update all 8 bytes of column for now, as each column in _attribute_column_dirty only stores 1 bit
+    ; As PPU has no increment-by-8 feature, split writes into 4 separate stripes 2 bytes each
+    ; TODO: Could make a dedicated unrolled transfer routine in nmi handler that writes all 8 bytes as one stripe.
+    i = 0
+    .rept 4
+    WRITEVERT
     i = i + 1
     .endm
     jmp _flush_shadow_attributes_columns_next_column

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