git.y1.nz

commit d6b2a80b0674a848d33a5bd942791a817118ed74
parent 5fa361b08e86bb90f3f74e680f9a5cb534781bff
Author: Toxa <56631470+untoxa@users.noreply.github.com>
Date:   Sat, 14 Mar 2026 12:17:18 +0300

Merge pull request #870 from bbbbbr/fix/apa_circle_radius
Diffstat:
M
gbdk-lib/include/gb/drawing.h
10
++++++++--
M
gbdk-lib/libc/targets/sm83/drawing.s
8
+++++++-

2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/gbdk-lib/include/gb/drawing.h b/gbdk-lib/include/gb/drawing.h
@@ -119,8 +119,14 @@ void line(uint8_t x1, uint8_t y1, uint8_t x2, uint8_t y2) OLDCALL;
    __style__ (one of NOFILL or FILL) */
 void box(uint8_t x1, uint8_t y1, uint8_t x2, uint8_t y2, uint8_t style) OLDCALL;
 
-/** Draw a circle with centre at __x,y__ and __radius__ using fill mode
-   __style__  (one of NOFILL or FILL)*/
+/** Draw a circle with center at __x,y__ and __radius__ using fill mode
+   __style__
+
+    @param x        X center location in pixels
+    @param y        Y center location in pixels
+    @param radius   Value between 1 and 254 (no draw for values outside range)
+    @param style    NOFILL or FILL
+   */
 void circle(uint8_t x, uint8_t y, uint8_t radius, uint8_t style) OLDCALL;
 
 /** Returns the current colour of the pixel at __x,y__ */
diff --git a/gbdk-lib/libc/targets/sm83/drawing.s b/gbdk-lib/libc/targets/sm83/drawing.s
@@ -1478,12 +1478,18 @@ _circle::
         LD      A,(HL+) ; C = y
         LD      C,A
         LD      A,(HL+) ; D = Radius
+        OR      A
+        JR      Z,$1    ; Don't draw circle of radius zero
+        INC     A
+        OR      A
+        JR      Z,$1    ; Radius of 255 not supported
+        DEC     A
         LD      D,A
         LD      A,(HL)
         LD      (.style),A
 
         CALL    .circle
-
+$1:
         POP     BC
         RET
 

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