to chapter 13

Chapter-11/datamap-multiple.m

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+
+#import <Foundation/Foundation.h>
+
+int main(int argc, char *argv[] ) {
+     [NSAutoreleasePool new];
+     int options=0;
+     printf("start\n");
+     if ( argv[2] ) {
+	 options=(atoi(argv[2])==1) ? NSDataReadingMappedAlways : atoi(argv[2])==2 ? NSDataReadingUncached : 0;
+     }
+     NSString *basePath = [NSString stringWithUTF8String:argv[1]];
+     NSFileManager *fm=[NSFileManager defaultManager];
+     NSArray *files=[fm contentsOfDirectoryAtPath:basePath  error:nil];
+    unsigned char result=0;
+    NSLog(@"%ld files option: %d",[files count],options);
+     for ( NSString *file in files ) {
+       @autoreleasepool {
+         NSString *relpath=[basePath stringByAppendingPathComponent: file];
+         NSURL *url=[NSURL fileURLWithPath:relpath isDirectory:NO];
+         NSData *data=[NSData dataWithContentsOfURL:url options:options error:nil];
+         unsigned stride=4096;
+         const char *bytes,*cur,*end;
+         for (bytes=[data bytes],end=bytes+[data length],cur=bytes; cur < end-stride; cur+=stride ) {
+             result ^= *cur;
+         }     
+      }
+    }
+    NSLog(@"result: %x",result);
+}

Chapter-11/datamapping-complex.m

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+
+#import <Foundation/Foundation.h>
+
+const char *readFileNSData( char *filename, int shouldMap, int uncached, long *size, int stride ) {
+     NSData *data;
+     NSURL *url=[NSURL fileURLWithPath:[NSString stringWithUTF8String:filename]];
+     int mapping = shouldMap ? NSDataReadingMappedAlways : uncached ? NSDataReadingUncached : 0 ;
+//     NSLog(@"file: %@, mapped: %d uncached: %d options:%d",url,shouldMap,uncached,mapping);
+     data=[NSData dataWithContentsOfURL:url options:mapping error:nil];
+     if ( shouldMap && stride <= 4096 ) {
+	madvise( (void*)[data bytes], [data length], MADV_SEQUENTIAL  | MADV_WILLNEED  );
+     }
+     if ( size ) {
+        *size=[data length];
+     }
+     return [data bytes];
+}
+
+const char *readFileUnix( char *filename, int shouldMap, int uncached, long *size ) {
+    int fd=open( filename, O_RDONLY);
+    off_t length=lseek(fd,0 , SEEK_END);
+    char *result=NULL;
+    NSLog(@"got fd: %d length: %lld",fd,length);
+    if ( size ) {  *size=length; }
+    if ( shouldMap ) {
+	//  MAP_PRIVATE, MAP_NOCACHE
+        result=mmap( NULL,  length, PROT_READ  , MAP_SHARED , fd, 0 );
+#if 1
+	    madvise( (void*)result, length, MADV_SEQUENTIAL | MADV_WILLNEED  );
+#endif
+    } else {
+	lseek(fd,0 , SEEK_SET);
+         result=malloc( length );
+         NSLog(@"got result buf: %p",result);
+         long long int numRead=read( fd, result, length );
+         NSLog(@"read %lld bytes",numRead);
+         if ( numRead <0 ) {
+            perror("couldn't read");
+         }
+    }
+    close(fd);
+    return result;
+}
+
+
+int main(int argc, char *argv[] ) {
+     [NSAutoreleasePool new];
+     char *filename=argv[1];
+     BOOL shouldMap=argv[2] && atoi(argv[2])==1;
+     BOOL uncached=argv[2] && atoi(argv[2])==2; 
+     int pageStride=argv[3] ? atoi(argv[3]) : 1;
+     int stride = pageStride * 4096 + 1;
+     char result=0;
+     long length=0;
+     const char *bytes=readFileNSData( filename, shouldMap, uncached, &length, stride );
+//     const char *bytes=readFileUnix( filename, shouldMap, uncached, &length );
+     const char *end=bytes+length;
+     const char *cur=bytes;
+//     NSLog(@"length: %ld stride=%d",length,stride);
+     while ( cur >= bytes && cur < end ) {
+         result ^= *cur;
+	 cur+=stride;
+     }     
+     NSLog(@"result: %x",result);
+}

Chapter-11/datamapping-simple.m

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+#import <Foundation/Foundation.h>
+int main(int argc, char *argv[] ) {
+    NSURL *url=[NSURL fileURLWithPath:@(argv[1])];
+    NSData *d=[NSData dataWithContentsOfURL:url options:0 error:nil];
+    char result=0;
+    const char *bytes=[d bytes];
+    const char *end=bytes+[d length];
+    for (const char *cur=bytes; cur < end; cur++ ) {
+      result ^= *cur;
+    }
+    printf("result: \%x\n",result);
+}

Chapter-11/datamapping.m

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+
+#import <Foundation/Foundation.h>
+
+int main(int argc, char *argv[] ) {
+     const unsigned char *bytes,*end,*cur;
+     int pageStride=argv[3] ? atoi(argv[3]) : 0;
+     int pageOffset=argv[4] ? atoi(argv[4]) : 0;
+     int stride = pageStride * 4096 +  pageOffset;
+     printf("pageStride: %d pageOffset: %d -> stride: %d\n",pageStride,pageOffset,stride);
+     int options = 0;
+     [NSAutoreleasePool new];
+     printf("start\n");
+     if ( argv[2] ) {
+	 options=(atoi(argv[2])==1) ? NSDataReadingMappedAlways : atoi(argv[2])==2 ? NSDataReadingUncached : 0;
+     }
+     NSURL *url=[NSURL fileURLWithPath:[NSString stringWithUTF8String:argv[1]] isDirectory:NO];
+     NSData *data=[NSData dataWithContentsOfURL:url options:options error:nil];
+     if ( 0 &&  options == NSDataReadingMappedAlways ) {
+        madvise( [data bytes],[data length], MADV_SEQUENTIAL | MADV_WILLNEED );
+         printf("madvise\n");
+     }
+     unsigned char result=0;
+     for (bytes=[data bytes],end=bytes+[data length],cur=bytes; cur < end-stride; cur+=stride ) {
+         result ^= *cur;
+     }     
+     printf("stride: %d result: %x\n",stride,result);
+    [data writeToFile:@"out" atomically:NO];
+}