From 4652da4af5886cd6ea5e61e418158707b768b907 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebastian=20Strohh=C3=A4cker?=
 <c2woody@users.sourceforge.net>
Date: Thu, 27 Nov 2008 18:57:45 +0000
Subject: [PATCH] add ems OS-dedicated handle functionality (fixes battle chess
 4000 screen bug, thanks to ripsaw for debugging this), fix some ems error
 numbers

Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@3241
---
 src/ints/ems.cpp | 63 ++++++++++++++++++++++++++++++++++++------------
 1 file changed, 47 insertions(+), 16 deletions(-)

diff --git a/src/ints/ems.cpp b/src/ints/ems.cpp
index 7a54ffb2..5f581f21 100644
--- a/src/ints/ems.cpp
+++ b/src/ints/ems.cpp
@@ -16,7 +16,7 @@
  *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
 
-/* $Id: ems.cpp,v 1.59 2008-10-05 14:44:52 qbix79 Exp $ */
+/* $Id: ems.cpp,v 1.60 2008-11-27 18:57:45 c2woody Exp $ */
 
 #include <string.h>
 #include <stdlib.h>
@@ -57,12 +57,14 @@
 #define EMM_INVALID_HANDLE		0x83
 #define EMM_FUNC_NOSUP			0x84
 #define EMM_OUT_OF_HANDLES		0x85
+#define EMM_SAVEMAP_ERROR		0x86
 #define EMM_OUT_OF_PHYS			0x87
 #define EMM_OUT_OF_LOG			0x88
 #define EMM_ZERO_PAGES			0x89
 #define EMM_LOG_OUT_RANGE		0x8a
 #define EMM_ILL_PHYS			0x8b
 #define EMM_PAGE_MAP_SAVED		0x8d
+#define EMM_NO_SAVED_PAGE_MAP	0x8e
 #define EMM_INVALID_SUB			0x8f
 #define EMM_FEAT_NOSUP			0x91
 #define EMM_MOVE_OVLAP			0x92
@@ -210,9 +212,11 @@ static bool INLINE ValidHandle(Bit16u handle) {
 	return true;
 }
 
-static Bit8u EMM_AllocateMemory(Bit16u pages,Bit16u & dhandle) {
+static Bit8u EMM_AllocateMemory(Bit16u pages,Bit16u & dhandle,bool can_allocate_zpages) {
 	/* Check for 0 page allocation */
-	if (!pages) return EMM_ZERO_PAGES;
+	if (!pages) {
+		if (!can_allocate_zpages) return EMM_ZERO_PAGES;
+	}
 	/* Check for enough free pages */
 	if ((MEM_FreeTotal()/ 4) < pages) { return EMM_OUT_OF_LOG;}
 	Bit16u handle = 1;
@@ -229,6 +233,21 @@ static Bit8u EMM_AllocateMemory(Bit16u pages,Bit16u & dhandle) {
 	return EMM_NO_ERROR;
 }
 
+static Bit8u EMM_AllocateSystemHandle(Bit16u pages) {
+	/* Check for enough free pages */
+	if ((MEM_FreeTotal()/ 4) < pages) { return EMM_OUT_OF_LOG;}
+	Bit16u handle = 0;	// emm system handle (reserved for OS usage)
+	/* Release memory if already allocated */
+	if (emm_handles[handle].pages != NULL_HANDLE) {
+		MEM_ReleasePages(emm_handles[handle].mem);
+	}
+	MemHandle mem = MEM_AllocatePages(pages*4,false);
+	if (!mem) E_Exit("EMS:System handle memory allocation failure");
+	emm_handles[handle].pages = pages;
+	emm_handles[handle].mem = mem;
+	return EMM_NO_ERROR;
+}
+
 static Bit8u EMM_ReallocatePages(Bit16u handle,Bit16u & pages) {
 	/* Check for valid handle */
 	if (!ValidHandle(handle)) return EMM_INVALID_HANDLE;
@@ -328,10 +347,16 @@ static Bit8u EMM_MapSegment(Bitu segment,Bit16u handle,Bit16u log_page) {
 static Bit8u EMM_ReleaseMemory(Bit16u handle) {
 	/* Check for valid handle */
 	if (!ValidHandle(handle)) return EMM_INVALID_HANDLE;
+	// should check for saved_page_map flag here, returning an error if it's true
+	// as apps are required to restore the pagemap beforehand; to be checked
 	MEM_ReleasePages(emm_handles[handle].mem);
 	/* Reset handle */
 	emm_handles[handle].mem=0;
-	emm_handles[handle].pages=NULL_HANDLE;
+	if (handle==0) {
+		emm_handles[handle].pages=0;	// OS handle is NEVER deallocated
+	} else {
+		emm_handles[handle].pages=NULL_HANDLE;
+	}
 	emm_handles[handle].saved_page_map=false;
 	memset(&emm_handles[handle].name,0,8);
 	return EMM_NO_ERROR;
@@ -372,7 +397,7 @@ static Bit8u EMM_RestorePageMap(Bit16u handle) {
 		if (handle!=0) return EMM_INVALID_HANDLE;
 	}
 	/* Check for previous save */
-	if (!emm_handles[handle].saved_page_map) return EMM_INVALID_HANDLE;
+	if (!emm_handles[handle].saved_page_map) return EMM_NO_SAVED_PAGE_MAP;
 	/* Restore the mappings */
 	emm_handles[handle].saved_page_map=false;
 	for (Bitu i=0;i<EMM_MAX_PHYS;i++) {
@@ -474,11 +499,11 @@ static Bit8u HandleNameSearch(void) {
 		return EMM_NOT_FOUND;
 		break;
 	case 0x02: /* Get Total number of handles */
-	  reg_bx=EMM_MAX_HANDLES;
-	  break;
+		reg_bx=EMM_MAX_HANDLES;
+		break;
 	default:
 		LOG(LOG_MISC,LOG_ERROR)("EMS:Call %2X Subfunction %2X not supported",reg_ah,reg_al);
-		return EMM_FUNC_NOSUP;
+		return EMM_INVALID_SUB;
 	}
 	return EMM_NO_ERROR;
 }
@@ -496,7 +521,7 @@ static Bit8u GetSetHandleName(void) {
 		break;
 	default:
 		LOG(LOG_MISC,LOG_ERROR)("EMS:Call %2X Subfunction %2X not supported",reg_ah,reg_al);
-		return EMM_FUNC_NOSUP;
+		return EMM_INVALID_SUB;
 	}
 	return EMM_NO_ERROR;
 
@@ -630,7 +655,7 @@ static Bitu INT67_Handler(void) {
 		reg_ah=EMM_NO_ERROR;
 		break;
 	case 0x43:		/* Get Handle and Allocate Pages */
-		reg_ah=EMM_AllocateMemory(reg_bx,reg_dx);
+		reg_ah=EMM_AllocateMemory(reg_bx,reg_dx,false);
 		break;
 	case 0x44:		/* Map Expanded Memory Page */
 		reg_ah=EMM_MapPage(reg_al,reg_dx,reg_bx);
@@ -682,7 +707,7 @@ static Bitu INT67_Handler(void) {
 			break;
 		default:
 			LOG(LOG_MISC,LOG_ERROR)("EMS:Call %2X Subfunction %2X not supported",reg_ah,reg_al);
-			reg_ah=EMM_FUNC_NOSUP;
+			reg_ah=EMM_INVALID_SUB;
 			break;
 		}
 		break;
@@ -710,6 +735,10 @@ static Bitu INT67_Handler(void) {
 					};
 				}
 				break;
+			default:
+				LOG(LOG_MISC,LOG_ERROR)("EMS:Call %2X Subfunction %2X not supported",reg_ah,reg_al);
+				reg_ah=EMM_INVALID_SUB;
+				break;
 		}
 		break;
 	case 0x51:	/* Reallocate Pages */
@@ -739,11 +768,11 @@ static Bitu INT67_Handler(void) {
 		reg_ah = EMM_NO_ERROR;
 		break;
 	case 0x5A:              /* Allocate standard/raw Pages */
-		if (reg_al==0x00) {
-			reg_ah=EMM_AllocateMemory(reg_bx,reg_dx);
+		if (reg_al<=0x01) {
+			reg_ah=EMM_AllocateMemory(reg_bx,reg_dx,true);	// can allocate 0 pages
 		} else {
 			LOG(LOG_MISC,LOG_ERROR)("EMS:Call 5A subfct %2X not supported",reg_al);
-			reg_ah=EMM_FUNC_NOSUP;
+			reg_ah=EMM_INVALID_SUB;
 		};
 		break;
 	case 0xDE:		/* VCPI Functions */
@@ -1130,7 +1159,7 @@ static void SetupVCPI() {
 	vcpi.pic2_remapping=0x70;	// slave PIC base
 
 	/* Allocate one EMS-page for private VCPI-data in memory beyond 1MB */
-	EMM_AllocateMemory(1,vcpi.ems_handle);
+	EMM_AllocateMemory(1,vcpi.ems_handle,false);
 	vcpi.private_area=emm_handles[vcpi.ems_handle].mem<<12;
 
 	/* GDT */
@@ -1212,7 +1241,7 @@ private:
 public:
 	EMS(Section* configuration):Module_base(configuration){
 
-	/* Virtual DMA interrupt callback */
+		/* Virtual DMA interrupt callback */
 		call_vdma.Install(&INT4B_Handler,CB_IRET,"Int 4b vdma");
 		call_vdma.Set_RealVec(0x4b);
 
@@ -1261,6 +1290,8 @@ public:
 			emm_segmentmappings[i].handle=NULL_HANDLE;
 		}
 
+		EMM_AllocateSystemHandle(4);	// allocate OS-dedicated handle (ems handle zero)
+
 		if (!ENABLE_VCPI) return;
 
 		/* Install a callback that handles VCPI-requests in protected mode requests */