git.y1.nz

commit 0b45cdea99a2c15bfa3f9b00c34f80032d254b3b
parent c8c0d1048d5abd7a2aebf48f5942f14d41b07d07
Author: Toxa <untoxa@mail.ru>
Date:   Fri,  1 Mar 2024 19:44:39 +0300

GB: add clamping and use the new calling convention in set_bkg_tile_xy()/set_win_tile_xy()

Diffstat:
M
gbdk-lib/include/gb/gb.h
4
++--
M
gbdk-lib/libc/targets/sm83/set_tile.s
51
++++++++++++++++++++++++++++-----------------------

2 files changed, 30 insertions(+), 25 deletions(-)
diff --git a/gbdk-lib/include/gb/gb.h b/gbdk-lib/include/gb/gb.h
@@ -1359,7 +1359,7 @@ void get_bkg_tiles(uint8_t x, uint8_t y, uint8_t w, uint8_t h, uint8_t *tiles) O
 
     @return returns the address of tile, so you may use faster set_vram_byte() later
 */
-uint8_t * set_bkg_tile_xy(uint8_t x, uint8_t y, uint8_t t) OLDCALL PRESERVES_REGS(b, c);
+uint8_t * set_bkg_tile_xy(uint8_t x, uint8_t y, uint8_t t);
 #define set_tile_xy set_bkg_tile_xy
 
 /** Set single attribute data a on background layer at x,y
@@ -1659,7 +1659,7 @@ void get_win_tiles(uint8_t x, uint8_t y, uint8_t w, uint8_t h, uint8_t *tiles) O
  * @param t tile index
  * @return returns the address of tile, so you may use faster set_vram_byte() later
  */
-uint8_t * set_win_tile_xy(uint8_t x, uint8_t y, uint8_t t) OLDCALL PRESERVES_REGS(b, c);
+uint8_t * set_win_tile_xy(uint8_t x, uint8_t y, uint8_t t);
 
 
 /**
diff --git a/gbdk-lib/libc/targets/sm83/set_tile.s b/gbdk-lib/libc/targets/sm83/set_tile.s
@@ -10,43 +10,48 @@ _set_vram_byte::
         ret
 
 _set_win_tile_xy::
-        ldh     a,(.LCDC)
+        ld      d, a
+        ldh     a, (.LCDC)
         and     #LCDCF_WIN9C00
-        jr      z,.is98
+        jr      z, .is98
         jr      .is9c
+
 _set_bkg_tile_xy::
-        ldh     a,(.LCDC)
+        ld      d, a
+        ldh     a, (.LCDC)
         and     #LCDCF_BG9C00
-        jr      nz,.is9c
+        jr      nz, .is9c
 .is98:
-        ld      d,#0x98         ; DE = origin
+        ld      b, #0x98
         jr      .set_tile_xy
 .is9c:
-        ld      d,#0x9C         ; DE = origin
+        ld      b,#0x9C
 
-.set_tile_xy:
-        push    bc
-        ldhl    sp,#4
-
-        ld      a, (hl+)
-        ld      b, a
-        ld      a, (hl+)
+.set_tile_xy:                   ; DE = XY; B = origin
+        ld      l, #0x1f
+        ld      a, d
+        and     l
+        ld      d, a
+        ld      a, e
+        and     l
 
-        ld      e, d
+        ld      c, b
         swap    a
         rlca
-        ld      c, a
+        ld      e, a
         and     #0x03
-        add     e
-        ld      d, a
+        add     c
+        ld      b, a
         ld      a, #0xE0
-        and     c
-        add     b
-        ld      e, a            ; dest DE = BASE + 0x20 * Y + X
+        and     e
+        add     d
+        ld      c, a            ; dest BC = (BASE << 8) + 0x20 * Y + X
 
+        ldhl    sp, #2
         WAIT_STAT
         ld      a, (hl)
-        ld      (de), a
+        ld      (bc), a         ; return BC as result
 
-        pop     bc
-        ret
+        pop     hl
+        inc     sp
+        jp      (hl)

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