git.y1.nz

commit 05acfe9c3fa4b4100c554bec9fd0f8549b11ce70
parent 844c3b8cd003759af0ade639004a9ee375353913
Author: toxa <untoxa@mail.ru>
Date:   Tue,  3 Nov 2020 14:15:03 +0300

MUL8 macro, minor optimizations to mul.s

Diffstat:
M
gbdk-lib/libc/asm/gbz80/mul.s
8
++++----
M
gbdk-lib/libc/gb/global.s
15
+++++++++++++++

2 files changed, 19 insertions(+), 4 deletions(-)
diff --git a/gbdk-lib/libc/asm/gbz80/mul.s b/gbdk-lib/libc/asm/gbz80/mul.s
@@ -79,7 +79,7 @@ signexte:
         sbc     a,a
         ld      d,a
 
-        jp      .mul16
+        jr      .mul16
 
 __muluchar:
         ld      hl,#2
@@ -95,7 +95,7 @@ __muluchar:
         ld      d,a
         ld      b,a
 
-        jp      .mul16
+        jr      .mul16
 
 __mulint:
         ld      hl,#2
@@ -133,7 +133,7 @@ __mulint:
         ;; Optimise for the case when this side has 8 bits of data or
         ;; less.  This is often the case with support address calls.
         or      a
-        jp      NZ,1$
+        jr      NZ,1$
 
         ld      b,#8
         ld      a,c
@@ -143,7 +143,7 @@ __mulint:
         add     hl,hl
         rl      c
         rla                     ;DLE 27/11/98
-        jp      NC,2$
+        jr      NC,2$
         add     hl,de
 2$:
         dec     b
diff --git a/gbdk-lib/libc/gb/global.s b/gbdk-lib/libc/gb/global.s
@@ -182,3 +182,18 @@ lbl:
 	INC	A
 	SIGNED_ADD_A_REG16	regH, regL
 .endm
+
+.macro MUL8_DE_RET_HL reg8 ?lbl1 ?lbl2
+	; Multiply DE by B or C, return result in HL; preserves: BC, DE
+	LD	HL, #0
+	LD	A, #8
+lbl1:
+	ADD	HL, HL
+	RLC	reg8
+	JR	NC, lbl2
+	ADD	HL, DE
+lbl2:
+	DEC	A
+	JR	NZ, lbl1
+
+

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