From 5b8bfd26cd8d111af41437ab9d9ea6ff72110487 Mon Sep 17 00:00:00 2001
From: b1ackmai1er <difficultylevelhigh@gmail.com>
Date: Sat, 26 Dec 2020 01:38:21 +0800
Subject: [PATCH] Update md.asm

Further optimization of loops utilizing alternate register AF'
---
 Source/HBIOS/md.asm | 42 ++++++++++++++++++++++--------------------
 1 file changed, 22 insertions(+), 20 deletions(-)

diff --git a/Source/HBIOS/md.asm b/Source/HBIOS/md.asm
index 6ade72bb..dc130510 100644
--- a/Source/HBIOS/md.asm
+++ b/Source/HBIOS/md.asm
@@ -812,13 +812,20 @@ MD_FNCALL:
 #IF (MD_FDBG==1)
 	CALL	PRTHEXWORD
 #ENDIF
+;
+	EX	AF,AF'
+	PUSH	AF
+	LD	A,(HB_CURBNK)		; WE ARE STARTING IN HB_CURBNK
 ;
 	HB_DI
-	LD	(FF_SAVSTK),SP		; SAVE CURRENT STACK
+	LD	(MD_SAVSTK),SP		; SAVE CURRENT STACK
 	LD	SP,HBX_BUF_END		; SETUP A NEW HIMEM STACK AT END OF HX_BUF
 	CALL	HBX_BUF			; EXECUTE RELOCATED CODE
-	LD	SP,(FF_SAVSTK)		; RESTORE STACK
+	LD	SP,(MD_SAVSTK)		; RESTORE STACK
 	HB_EI
+;
+	POP	AF
+	EX	AF,AF'
 ;
 #IF (MD_FDBG==1)
 	CALL	PC_SPACE
@@ -835,7 +842,7 @@ MD_FNCALL:
 	POP	HL
 	RET				; RETURN TO MD_READF, MD_WRITEF
 ;
-FF_SAVSTK	.DW	0
+MD_SAVSTK	.DW	0
 ;
 ;======================================================================
 ; CALCULATE BANK AND ADDRESS DATA FROM MEMORY ADDRESS
@@ -843,7 +850,6 @@ FF_SAVSTK	.DW	0
 ; ON ENTRY DE:HL CONTAINS 32 BIT MEMORY ADDRESS.
 ; ON EXIT  B     CONTAINS BANK SELECT BYTE
 ;          C     CONTAINS HIGH BYTE OF SECTOR ADDRESS
-;          A     CONTAINS CURRENT BANK HB_CURBNK
 ;
 ; DDDDDDDDEEEEEEEE HHHHHHHHLLLLLLLL
 ; 3322222222221111 1111110000000000
@@ -875,8 +881,6 @@ MD_CALCA:
 	CALL	PRTHEXWORD	; DISPLAY BANK AND
 	CALL	PC_SPACE	; SECTOR RESULT
 #ENDIF
-;
-	LD	A,(HB_CURBNK)	; WE ARE STARTING IN HB_CURBNK
 ;
 	RET			
 ;
@@ -896,7 +900,7 @@ MD_CALCA:
 ;
 MD_FIDENT_R:				; THIS CODE GETS RELOCATED TO HIGH MEMORY
 ;
-	PUSH	AF			; SAVE CURRENT BANK
+	LD	D,A			; SAVE CURRENT BANK
 ;
 	LD	A,B			; SELECT BANK
 	CALL	HBX_BNKSEL		; TO PROGRAM
@@ -909,10 +913,10 @@ MD_FIDENT_R:				; THIS CODE GETS RELOCATED TO HIGH MEMORY
 ;					; LD	($5555),A
 	LD	BC,($0000)						; READ ID
 ;
-	LD	A,$F0			; 				; EXIT 
+	LD	A,$F0			; LD	A,$F0			; EXIT 
 	LD	(HL),A			; LD	($5555),A		; COMMAND
 ;
-	POP	AF			; RETURN TO ORIGINAL BANK
+	LD	A,D			; RETURN TO ORIGINAL BANK
 	JP	HBX_BNKSEL		; WHICH IS OUR RAM BIOS COPY
 ;
 ;	RET				
@@ -1040,7 +1044,7 @@ MD_R_SZ	.EQU	$-MD_FREAD_R		; SIZE OF RELOCATABLE CODE BUFFER REQUIRED
 ;          DE = 0000 BYTE COUNT
 ;          IX POINTS TO DATA TO BE VERIFIED
 ;          A  CONTAINS CURRENT BANK 
-; ON EXIT  NO STATUS RETURNED
+; ON EXIT  C  RETURNS STATUS 0=SUCCESS NZ=FAIL
 ;======================================================================
 ;
 MD_FVERI_R:				; THIS CODE GETS RELOCATED TO HIGH MEMORY
@@ -1048,20 +1052,18 @@ MD_FVERI_R:				; THIS CODE GETS RELOCATED TO HIGH MEMORY
 	LD	H,C			; SECTOR
 	LD	L,D			; ADDRESS
 ;
-	PUSH	AF			; SAVE CURRENT BANK
+	EX	AF,AF'			; PUT SOURCE BANK IN AF' (RAM)
 ;
 MD_FVE1:	
 	LD	A,B			; SELECT BANK
-	CALL	HBX_BNKSEL		; TO READ
-	LD	C,(HL)			; READ BYTE
+	CALL	HBX_BNKSEL		; TO READ 			; SWITCH TO FLASH BANK
+	LD	A,(HL)			; READ BYTE
 ;
-	POP	AF
-	PUSH	AF			; SELECT BANK
+	EX	AF,AF'			; SELECT BANK			; SWITCH TO RAM BANK
 	CALL	HBX_BNKSEL		; TO VERIFY AGAINST
+	EX	AF,AF'
 ;
-	LD	A,C
 	SUB	(IX+0)			; COMPARE BYTE
-	LD	C,A			; SET NON ZERO STATUS
 	JR	NZ,MD_FVE2		; EXIT IF MISMATCH
 ;
 	INC	HL			; NEXT SOURCE LOCATION
@@ -1070,11 +1072,11 @@ MD_FVE1:
 	INC	DE			; CONTINUE READING UNTIL
 	BIT	4,D			; WE HAVE DONE ONE SECTOR
 	JR	Z,MD_FVE1
-;
-	LD	C,E			; SET SUCCESS STATUS = 0
 ;
 MD_FVE2:
-	POP	AF
+	LD	C,A			; SET STATUS 
+	EX	AF,AF'
+;
 	RET				
 ;
 MD_V_SZ	.EQU	$-MD_FVERI_R		; SIZE OF RELOCATABLE CODE BUFFER REQUIRED