From 87f990907d1e9a6cc24ca2955f2c2ae324470af1 Mon Sep 17 00:00:00 2001
From: Ulf Wohlers <finsterr@users.sourceforge.net>
Date: Mon, 25 Nov 2002 11:37:04 +0000
Subject: [PATCH] Support for memory allocation strategy: last matching block

Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@535
---
 include/dos_inc.h      |  2 ++
 src/dos/dos.cpp        |  3 ++-
 src/dos/dos_memory.cpp | 46 +++++++++++++++++++++++++++++++++---------
 3 files changed, 40 insertions(+), 11 deletions(-)

diff --git a/include/dos_inc.h b/include/dos_inc.h
index ff3d7595..346c5a26 100644
--- a/include/dos_inc.h
+++ b/include/dos_inc.h
@@ -140,6 +140,8 @@ bool DOS_ResizeMemory(Bit16u segment,Bit16u * blocks);
 bool DOS_FreeMemory(Bit16u segment);
 void DOS_FreeProcessMemory(Bit16u pspseg);
 Bit16u DOS_GetMemory(Bit16u pages);
+void DOS_SetMemAllocStrategy(Bit16u strat);
+Bit16u DOS_GetMemAllocStrategy(void);
 
 /* FCB stuff */
 bool DOS_FCBOpen(Bit16u seg,Bit16u offset);
diff --git a/src/dos/dos.cpp b/src/dos/dos.cpp
index 75d0a798..5df2a3ab 100644
--- a/src/dos/dos.cpp
+++ b/src/dos/dos.cpp
@@ -679,9 +679,10 @@ static Bitu DOS_21Handler(void) {
 	case 0x58:					/* Get/Set Memory allocation strategy */
 		switch (reg_al) {
 		case 0:		/* Get Strategy */
-			reg_ax=0;			//Low memory first fit
+			reg_ax=DOS_GetMemAllocStrategy();
 			break;
 		case 1:		/* Set Strategy */
+			DOS_SetMemAllocStrategy(reg_bx);
 			break;
 		default:
 			LOG_DEBUG("DOS:58:Not Supported Set//Get memory allocation call %X",reg_al);
diff --git a/src/dos/dos_memory.cpp b/src/dos/dos_memory.cpp
index 0140655b..0fb72a38 100644
--- a/src/dos/dos_memory.cpp
+++ b/src/dos/dos_memory.cpp
@@ -24,6 +24,7 @@
 #define MEM_START 0x60					//First Segment that DOS can use
 //#define MEM_START 4000					//First Segment that DOS can use
 
+static Bit16u memAllocStrategy = 0x00;
 
 static void DOS_CompressMemory(void) {
 	MCB * pmcb;MCB * pmcbnext;
@@ -57,6 +58,15 @@ void DOS_FreeProcessMemory(Bit16u pspseg) {
 	DOS_CompressMemory();
 };
 
+Bit16u DOS_GetMemAllocStrategy()
+{
+	return memAllocStrategy;
+};
+
+void DOS_SetMemAllocStrategy(Bit16u strat)
+{
+	memAllocStrategy = strat;
+};
 
 bool DOS_AllocateMemory(Bit16u * segment,Bit16u * blocks) {
 	MCB * pmcb;MCB * pmcbnext;
@@ -77,17 +87,33 @@ bool DOS_AllocateMemory(Bit16u * segment,Bit16u * blocks) {
 				*segment=mcb_segment+1;
 				return true;
 			} else {
+				// TODO: Strategy "1": Best matching block
 				/* If so allocate it */
-				pmcbnext=(MCB *)HostMake(mcb_segment+*blocks+1,0);
-				pmcbnext->psp_segment=MCB_FREE;
-				pmcbnext->type=pmcb->type;
-				pmcbnext->size=pmcb->size-*blocks-1;
-				pmcb->size=*blocks;
-				pmcb->type=0x4D;
-				pmcb->psp_segment=dos.psp;
-				//TODO Filename
-				*segment=mcb_segment+1;
-				return true;
+				if ((memAllocStrategy & 0x03)==0) {				
+					pmcbnext=(MCB *)HostMake(mcb_segment+*blocks+1,0);
+					pmcbnext->psp_segment=MCB_FREE;
+					pmcbnext->type=pmcb->type;
+					pmcbnext->size=pmcb->size-*blocks-1;
+					pmcb->size=*blocks;
+					pmcb->type=0x4D;
+					pmcb->psp_segment=dos.psp;
+					//TODO Filename
+					*segment=mcb_segment+1;
+					return true;
+				} else {
+					// * Last Block *
+					// New created block
+					*segment = mcb_segment+1+pmcb->size-*blocks;
+					pmcbnext=(MCB *)HostMake(*segment-1,0);
+					pmcbnext->size			= *blocks;
+					pmcbnext->type			= pmcb->type;
+					pmcbnext->psp_segment	= dos.psp;
+					// Old Block
+					pmcb->size				= pmcb->size-*blocks-1;
+					pmcb->psp_segment		= MCB_FREE;
+					pmcb->type				= 0x4D;
+					return true;
+				};
 			}
 		}
 		/* Onward to the next MCB if there is one */