git.y1.nz

commit adc683f778fed0c477bd6cf53cf3ca3f54b57b7d
parent 42875e72fea3f6d3addff3799136212e49d611fe
Author: Toxa <untoxa@mail.ru>
Date:   Sat,  4 Sep 2021 12:36:31 +0300

SMS/GG: delay()

Diffstat:
M
gbdk-lib/include/gb/gb.h
2
+-
M
gbdk-lib/include/sms/sms.h
7
+++++++
A
gbdk-lib/libc/targets/z80/delay.s
54
++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
gbdk-lib/libc/targets/z80/gg/Makefile
1
+
M
gbdk-lib/libc/targets/z80/gg/global.s
2
++
M
gbdk-lib/libc/targets/z80/sms/Makefile
1
+
M
gbdk-lib/libc/targets/z80/sms/global.s
2
++

7 files changed, 68 insertions(+), 1 deletion(-)
diff --git a/gbdk-lib/include/gb/gb.h b/gbdk-lib/include/gb/gb.h
@@ -503,7 +503,7 @@ __endasm; \
 
 /** Delays the given number of milliseconds.
     Uses no timers or interrupts, and can be called with
-    interrupts disabled (why nobody knows :)
+    interrupts disabled
  */
 void delay(uint16_t d) NONBANKED;
 
diff --git a/gbdk-lib/include/sms/sms.h b/gbdk-lib/include/sms/sms.h
@@ -349,6 +349,13 @@ __endasm; \
 #define DISABLE_RAM RAM_CONTROL&=(~RAMCTL_RAM)
 
 
+/** Delays the given number of milliseconds.
+    Uses no timers or interrupts, and can be called with
+    interrupts disabled
+ */
+void delay(uint16_t d) __z88dk_fastcall;
+
+
 /** Reads and returns the current state of the joypad.
 */
 uint8_t joypad(void) __preserves_regs(b, c, d, e, h, iyh, iyl);
diff --git a/gbdk-lib/libc/targets/z80/delay.s b/gbdk-lib/libc/targets/z80/delay.s
@@ -0,0 +1,53 @@
+        .include        "global.s"
+
+        .title  "Delay"
+        .module delay
+
+        .area _CODE
+
+;; hl must contain amount of tstates, which must be >= 141
+wait_hl_tstates::
+        ld bc, #-141
+        add hl, bc
+        ld bc, #-23
+1$:
+        add hl,bc
+        jr c, 1$
+        ld a, l
+        add a, #15
+        jr nc, 2$
+        cp #8
+        jr c, 3$
+        or #0
+2$:
+        inc hl
+3$:
+        rra
+        jr c, 4$
+        nop
+4$:
+        rra
+        jr nc, 5$   
+        or #0
+5$:
+        rra
+        ret nc
+        ret
+
+;; hl = milliseconds (0 = 65536)
+_delay::
+        ld e, l
+        ld d, h
+1$:
+        dec de
+        ld a,d
+        or e
+        jr z, 2$
+
+        ld hl,#((.CPU_CLOCK / 1000) - 43)
+        call wait_hl_tstates
+        jr 1$
+2$:
+        ld hl,#((.CPU_CLOCK / 1000) - 54)
+        jp wait_hl_tstates
+        ret
+
diff --git a/gbdk-lib/libc/targets/z80/gg/Makefile b/gbdk-lib/libc/targets/z80/gg/Makefile
@@ -25,6 +25,7 @@ ASSRC =	set_interrupts.s \
 	pad.s pad_ex.s \
 	int.s nmi.s \
 	mode.s \
+	delay.s \
 	memset_small.s \
 	far_ptr.s \
 	__sdcc_bcall.s \
diff --git a/gbdk-lib/libc/targets/z80/gg/global.s b/gbdk-lib/libc/targets/z80/gg/global.s
@@ -162,6 +162,8 @@
         .SYSTEM_PAL     = 0x00
         .SYSTEM_NTSC    = 0x01
 
+        .CPU_CLOCK      = 3574000
+
         ;; GBDK library screen modes
 
         .T_MODE         = 0x02  ; Text mode (bit 2)
diff --git a/gbdk-lib/libc/targets/z80/sms/Makefile b/gbdk-lib/libc/targets/z80/sms/Makefile
@@ -25,6 +25,7 @@ ASSRC =	set_interrupts.s \
 	pad.s pad_ex.s \
 	int.s nmi.s \
 	mode.s \
+	delay.s \
 	memset_small.s \
 	far_ptr.s \
 	__sdcc_bcall.s \
diff --git a/gbdk-lib/libc/targets/z80/sms/global.s b/gbdk-lib/libc/targets/z80/sms/global.s
@@ -162,6 +162,8 @@
         .SYSTEM_PAL     = 0x00
         .SYSTEM_NTSC    = 0x01
 
+        .CPU_CLOCK      = 3574000
+
         ;; GBDK library screen modes
 
         .T_MODE         = 0x02  ; Text mode (bit 2)

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