[hackers] [blind] Improve performance of blind-flop || Mattias Andrée

[git]

commit e19ed379f9d86c8a21515095fd8725c68f7b4426
Author:     Mattias Andrée <maand...@kth.se>
AuthorDate: Mon May 8 22:25:24 2017 +0200
Commit:     Mattias Andrée <maand...@kth.se>
CommitDate: Mon May 8 22:25:24 2017 +0200

    Improve performance of blind-flop
    
    Signed-off-by: Mattias Andrée <maand...@kth.se>

diff --git a/src/blind-flop.c b/src/blind-flop.c
index 3401f7d..c5826be 100644
--- a/src/blind-flop.c
+++ b/src/blind-flop.c
@@ -8,12 +8,28 @@
 
 USAGE("")
 
+static struct stream stream;
+static char *buf, *image;
+static size_t n, m, ps;
+
+#define PROCESS(TYPE)\
+       do {\
+               size_t i, j, pst = ps / sizeof(TYPE);\
+               size_t nt = n / sizeof(TYPE);\
+               size_t mt = m / sizeof(TYPE);\
+               for (i = 0; i < pst; i++)\
+                       for (j = 0; j < nt; j += pst)\
+                               ((TYPE *)image)[mt - j + i] = ((TYPE *)buf)[i + 
j];\
+       } while (0)
+
+static void process_double(void) {PROCESS(double);}
+static void process_float (void) {PROCESS(float);}
+static void process_char  (void) {PROCESS(char);}
+
 int
 main(int argc, char *argv[])
 {
-       struct stream stream;
-       char *buf, *image;
-       size_t i, j, n, m;
+       void (*process)(void);
 
        UNOFLAGS(argc);
 
@@ -22,15 +38,16 @@ main(int argc, char *argv[])
        efflush(stdout, "<stdout>");
 
        echeck_frame_size(stream.width, 1, stream.pixel_size, 0, stream.file);
-       n = stream.width * stream.pixel_size;
+       n = stream.width * (ps = stream.pixel_size);
        buf   = emalloc(n);
        image = emalloc(n);
 
-       m = n - stream.pixel_size;
+       process = !(ps % sizeof(double)) ? process_double :
+                 !(ps % sizeof(float))  ? process_float  : process_char;
+
+       m = n - ps;
        while (eread_row(&stream, buf, n)) {
-               for (i = 0; i < stream.pixel_size; i++)
-                       for (j = 0; j < n; j += stream.pixel_size)
-                               image[m - j + i] = buf[i + j];
+               process();
                ewriteall(STDOUT_FILENO, image, n, "<stdout>");
        }
 
diff --git a/src/blind-transpose.c b/src/blind-transpose.c
index 5c53a0d..cc7e7d3 100644
--- a/src/blind-transpose.c
+++ b/src/blind-transpose.c
@@ -33,7 +33,7 @@ main(int argc, char *argv[])
        struct stream stream;
        char *buf, *image;
        size_t n, y;
-       void (*process)(char *col, char *row);
+       void (*process)(char *row, char *col);
 
        UNOFLAGS(argc);