From 01d43035d5b3227ad7c9fafad82e77a559ecd74a Mon Sep 17 00:00:00 2001
From: cebix <>
Date: Fri, 13 Oct 2000 16:47:52 +0000
Subject: [PATCH] - replaced floating-point page shift calculation by integer
 routine, fixing   the VOSF problems under NetBSD/m68k - fixed off-by-7 error
 in 1-bit window update routines

---
 BasiliskII/src/Unix/video_vosf.h |  9 +++++++--
 BasiliskII/src/Unix/video_x.cpp  | 18 ++++++++++++++----
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/BasiliskII/src/Unix/video_vosf.h b/BasiliskII/src/Unix/video_vosf.h
index f409b10e..f5f5ba44 100644
--- a/BasiliskII/src/Unix/video_vosf.h
+++ b/BasiliskII/src/Unix/video_vosf.h
@@ -327,7 +327,12 @@ static bool Screen_fault_handler_init()
 	// Setup SIGSEGV handler to process writes to frame buffer
 	sigemptyset(&vosf_sa.sa_mask);
 	vosf_sa.sa_handler = (void (*)(int)) Screen_fault_handler;
+#if !EMULATED_68K && defined(__NetBSD__)
+	sigaddset(&vosf_sa.sa_mask, SIGALRM);
+	vosf_sa.sa_flags = SA_ONSTACK;
+#else
 	vosf_sa.sa_flags = 0;
+#endif
 	return (sigaction(SIGSEGV, &vosf_sa, NULL) == 0);
 }
 #endif
@@ -355,7 +360,7 @@ static inline void update_display_window_vosf(void)
 			PFLAG_CLEAR(page);
 			++page;
 		}
-		
+
 		// Make the dirty pages read-only again
 		const int32 offset  = first_page << mainBuffer.pageBits;
 		const uint32 length = (page - first_page) << mainBuffer.pageBits;
@@ -393,7 +398,7 @@ static inline void update_display_window_vosf(void)
 				uint8 * const p2 = &the_buffer_copy[j * bytes_per_row];
 				for (i = (VideoMonitor.x>>3) - 1; i > (x2>>3); i--) {
 					if (p1[i] != p2[i]) {
-						x2 = i << 3;
+						x2 = (i << 3) + 7;
 						break;
 					}
 				}
diff --git a/BasiliskII/src/Unix/video_x.cpp b/BasiliskII/src/Unix/video_x.cpp
index 89508a88..9198ced0 100644
--- a/BasiliskII/src/Unix/video_x.cpp
+++ b/BasiliskII/src/Unix/video_x.cpp
@@ -53,7 +53,6 @@
 #endif
 
 #ifdef ENABLE_VOSF
-# include <math.h> // log()
 # include <unistd.h>
 # include <signal.h>
 # include <fcntl.h>
@@ -219,6 +218,17 @@ static struct sigaction vosf_sa;
 static pthread_mutex_t Screen_draw_lock = PTHREAD_MUTEX_INITIALIZER;	// Mutex to protect frame buffer (dirtyPages in fact)
 #endif
 
+static int log_base_2(uint32 x)
+{
+	uint32 mask = 0x80000000;
+	int l = 31;
+	while (l >= 0 && (x & mask) == 0) {
+		mask >>= 1;
+		l--;
+	}
+	return l;
+}
+
 #endif
 
 // VideoRefresh function
@@ -804,7 +814,7 @@ bool VideoInitBuffer()
 
 		mainBuffer.pageSize     = page_size;
 		mainBuffer.pageCount	= (mainBuffer.memLength + page_mask)/mainBuffer.pageSize;
-		mainBuffer.pageBits     = int( log(mainBuffer.pageSize) / log(2.0) );
+		mainBuffer.pageBits     = log_base_2(mainBuffer.pageSize);
 
 		if (mainBuffer.dirtyPages != 0)
 			free(mainBuffer.dirtyPages);
@@ -1766,12 +1776,12 @@ static void update_display_static(void)
 				for (i=(VideoMonitor.x>>3); i>(x2>>3); i--) {
 					p--; p2--;
 					if (*p != *p2) {
-						x2 = i << 3;
+						x2 = (i << 3) + 7;
 						break;
 					}
 				}
 			}
-			wide = x2 - x1;
+			wide = x2 - x1 + 1;
 
 			// Update copy of the_buffer
 			if (high && wide) {