From 1f2b35fef2d09effc2f7f2016a65adc82f828bac Mon Sep 17 00:00:00 2001
From: kanjitalk755 <kanjitalk755@yahoo.co.jp>
Date: Wed, 12 Aug 2020 11:39:58 +0900
Subject: [PATCH] reserve framebuffer

---
 BasiliskII/src/CrossPlatform/vm_alloc.cpp | 11 ++++++++++-
 BasiliskII/src/CrossPlatform/vm_alloc.h   |  2 ++
 BasiliskII/src/SDL/video_sdl2.cpp         |  6 +++++-
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/BasiliskII/src/CrossPlatform/vm_alloc.cpp b/BasiliskII/src/CrossPlatform/vm_alloc.cpp
index 005cb727..cc51bd29 100755
--- a/BasiliskII/src/CrossPlatform/vm_alloc.cpp
+++ b/BasiliskII/src/CrossPlatform/vm_alloc.cpp
@@ -222,6 +222,13 @@ void vm_exit(void)
 #endif
 }
 
+static void *reserved_buf;
+static const size_t RESERVED_SIZE = 64 * 1024 * 1024; // for 5K Retina
+
+void *vm_acquire_reserved(size_t size) {
+	return reserved_buf && size <= RESERVED_SIZE ? reserved_buf : VM_MAP_FAILED;
+}
+
 /* Allocate zero-filled memory of SIZE bytes. The mapping is private
    and default protection bits are read / write. The return value
    is the actual mapping address chosen or VM_MAP_FAILED for errors.  */
@@ -243,11 +250,13 @@ void * vm_acquire(size_t size, int options)
 
 #if defined(HAVE_MACH_VM)
 	// vm_allocate() returns a zero-filled memory region
-	kern_return_t ret_code = vm_allocate(mach_task_self(), (vm_address_t *)&addr, size, TRUE);
+	kern_return_t ret_code = vm_allocate(mach_task_self(), (vm_address_t *)&addr, reserved_buf ? size : size + RESERVED_SIZE, TRUE);
 	if (ret_code != KERN_SUCCESS) {
 		errno = vm_error(ret_code);
 		return VM_MAP_FAILED;
 	}
+	if (!reserved_buf)
+		reserved_buf = (char *)addr + size;
 #elif defined(HAVE_MMAP_VM)
 	int fd = zero_fd;
 	int the_map_flags = translate_map_flags(options) | map_flags;
diff --git a/BasiliskII/src/CrossPlatform/vm_alloc.h b/BasiliskII/src/CrossPlatform/vm_alloc.h
index c44e853b..bc5aba97 100644
--- a/BasiliskII/src/CrossPlatform/vm_alloc.h
+++ b/BasiliskII/src/CrossPlatform/vm_alloc.h
@@ -99,6 +99,8 @@ extern void vm_exit(void);
 
 extern void * vm_acquire(size_t size, int options = VM_MAP_DEFAULT);
 
+extern void * vm_acquire_reserved(size_t size);
+
 /* Allocate zero-filled memory at exactly ADDR (which must be page-aligned).
    Returns 0 if successful, -1 on errors.  */
 
diff --git a/BasiliskII/src/SDL/video_sdl2.cpp b/BasiliskII/src/SDL/video_sdl2.cpp
index a17921a6..2dc0a3ca 100644
--- a/BasiliskII/src/SDL/video_sdl2.cpp
+++ b/BasiliskII/src/SDL/video_sdl2.cpp
@@ -215,6 +215,9 @@ extern void SysMountFirstFloppy(void);
 
 static void *vm_acquire_framebuffer(uint32 size)
 {
+#ifdef HAVE_MACH_VM
+	return vm_acquire_reserved(size);
+#else
 	// always try to reallocate framebuffer at the same address
 	static void *fb = VM_MAP_FAILED;
 	if (fb != VM_MAP_FAILED) {
@@ -228,11 +231,12 @@ static void *vm_acquire_framebuffer(uint32 size)
 	if (fb == VM_MAP_FAILED)
 		fb = vm_acquire(size, VM_MAP_DEFAULT | VM_MAP_32BIT);
 	return fb;
+#endif
 }
 
 static inline void vm_release_framebuffer(void *fb, uint32 size)
 {
-	vm_release(fb, size);
+//	vm_release(fb, size);
 }
 
 static inline int get_customized_color_depth(int default_depth)