git.y1.nz

commit f177cf413f1422c54d442219e99c544383131e93
parent 7a411e64cc2d4940dc04906f73a9ac3c68adbb41
Author: Toxa <untoxa@mail.ru>
Date:   Fri, 14 Jan 2022 16:09:56 +0300

GB/MD/AP: check for overflow in metasprites routines

Diffstat:
M
gbdk-lib/libc/targets/gbz80/metasprites.s
10
++++++++--
M
gbdk-lib/libc/targets/gbz80/metasprites_flip.s
30
++++++++++++++++++++++++------
M
gbdk-lib/libc/targets/gbz80/metasprites_hide.s
14
++++++++++++--
M
gbdk-lib/libc/targets/gbz80/metasprites_hide_spr.s
5
++++-

4 files changed, 48 insertions(+), 11 deletions(-)
diff --git a/gbdk-lib/libc/targets/gbz80/metasprites.s b/gbdk-lib/libc/targets/gbz80/metasprites.s
@@ -28,6 +28,9 @@ ___move_metasprite::
         ld      a, (hl-)
         ld      c, a
         ld      a, (hl)
+        cp      #40
+        jr      nc, 3$
+
         add     a
         add     a
         ld      e, a
@@ -64,12 +67,15 @@ ___move_metasprite::
         ld      (de), a
         inc     e
 
-        jr      1$
+        ld      a, e
+        cp      #160
+        jr      c, 1$
 2$:
-        ldhl    sp, #2
         ld      a, e
         srl     a
         srl     a
+        ldhl    sp, #2
+3$:
         sub     (hl)
         ld      e, a
 
diff --git a/gbdk-lib/libc/targets/gbz80/metasprites_flip.s b/gbdk-lib/libc/targets/gbz80/metasprites_flip.s
@@ -18,6 +18,9 @@ ___move_metasprite_hflip::
         ld      a, (hl-)
         ld      c, a
         ld      a, (hl)
+        cp      #40
+        jr      nc, 3$
+
         add     a
         add     a
         ld      e, a
@@ -57,12 +60,15 @@ ___move_metasprite_hflip::
         ld      (de), a
         inc     e
 
-        jr      1$
+        ld      a, e
+        cp      #160
+        jr      c, 1$
 2$:
-        ldhl    sp, #2
         ld      a, e
         srl     a
         srl     a
+        ldhl    sp, #2
+3$:
         sub     (hl)
         ld      e, a
 
@@ -75,6 +81,9 @@ ___move_metasprite_vflip::
         ld      a, (hl-)
         ld      c, a
         ld      a, (hl)
+        cp      #40
+        jr      nc, 3$
+
         add     a
         add     a
         ld      e, a
@@ -114,12 +123,15 @@ ___move_metasprite_vflip::
         ld      (de), a
         inc     e
 
-        jr      1$
+        ld      a, e
+        cp      #160
+        jr      c, 1$
 2$:
-        ldhl    sp, #2
         ld      a, e
         srl     a
         srl     a
+        ldhl    sp, #2
+3$:
         sub     (hl)
         ld      e, a
 
@@ -132,6 +144,9 @@ ___move_metasprite_hvflip::
         ld      a, (hl-)
         ld      c, a
         ld      a, (hl)
+        cp      #40
+        jr      nc, 3$
+
         add     a
         add     a
         ld      e, a
@@ -173,12 +188,15 @@ ___move_metasprite_hvflip::
         ld      (de), a
         inc     e
 
-        jr      1$
+        ld      a, e
+        cp      #160
+        jr      c, 1$
 2$:
-        ldhl    sp, #2
         ld      a, e
         srl     a
         srl     a
+        ldhl    sp, #2
+3$:
         sub     (hl)
         ld      e, a
 
diff --git a/gbdk-lib/libc/targets/gbz80/metasprites_hide.s b/gbdk-lib/libc/targets/gbz80/metasprites_hide.s
@@ -12,7 +12,10 @@
 
 ___hide_metasprite::
         ldhl    sp, #2
-        ld      a, (hl-)
+        ld      a, (hl)
+        cp      #40
+        ret     nc
+        
         add     a
         add     a
         ld      e, a
@@ -40,4 +43,10 @@ ___hide_metasprite::
         inc     e
         inc     e
         inc     e
-        jr      1$
+
+        ld      a, e
+        cp      #160
+
+        jr      c, 1$
+
+        ret
+
diff --git a/gbdk-lib/libc/targets/gbz80/metasprites_hide_spr.s b/gbdk-lib/libc/targets/gbz80/metasprites_hide_spr.s
@@ -13,6 +13,9 @@ _hide_sprites_range::
         ldhl    sp, #2
         ld      a, (hl+)
 
+        cp      #40
+        ret     nc
+
         add     a
         add     a
         ld      e, a
@@ -38,7 +41,7 @@ _hide_sprites_range::
         ret     z               ; z is not affected by 16-bit add
 
 0$:
-        rra                     ; carry is never set here
+        srl     a
         jr      nc, 1$
 
         ld      (hl), d

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