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

[git]

commit 4ff63fa07d63f27fef3583997b2c29188771dd6b
Author:     Mattias Andrée <maand...@kth.se>
AuthorDate: Mon May 8 23:04:15 2017 +0200
Commit:     Mattias Andrée <maand...@kth.se>
CommitDate: Mon May 8 23:04:15 2017 +0200

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

diff --git a/src/blind-convert.c b/src/blind-convert.c
index e26e304..32ab2c2 100644
--- a/src/blind-convert.c
+++ b/src/blind-convert.c
@@ -2,26 +2,31 @@
 #include "stream.h"
 #include "util.h"
 
+#include <alloca.h>
 #include <string.h>
 
 USAGE("pixel-format ...")
 
-static void (*outconv)(double x, double y, double z, double a);
+static void (*outconv)(double *xyzas, size_t n);
 
 #define INCONV(TYPE)\
        do {\
-               TYPE *pixel, x, y, z, a;\
-               size_t n;\
+               double buf[sizeof(stream->buf) / (4 * sizeof(TYPE)) * 4];\
+               double *interm;\
+               TYPE *in;\
+               size_t n, m;\
                do {\
-                       pixel = (TYPE *)stream->buf;\
-                       for (n = stream->ptr / stream->pixel_size; n--; pixel 
+= 4) {\
-                               x = (TYPE)(pixel[0]);\
-                               y = (TYPE)(pixel[1]);\
-                               z = (TYPE)(pixel[2]);\
-                               a = (TYPE)(pixel[3]);\
-                               outconv(x, y, z, a);\
+                       in = (TYPE *)stream->buf;\
+                       interm = buf;\
+                       n = stream->ptr / stream->pixel_size;\
+                       for (m = n; m--; in += 4, interm += 4) { \
+                               interm[0] = (TYPE)(in[0]);\
+                               interm[1] = (TYPE)(in[1]);\
+                               interm[2] = (TYPE)(in[2]);\
+                               interm[3] = (TYPE)(in[3]);\
                        }\
-                       n = stream->ptr - (stream->ptr % stream->pixel_size);\
+                       outconv(buf, n);\
+                       n *= stream->pixel_size;\
                        memmove(stream->buf, stream->buf + n, stream->ptr -= 
n);\
                } while (eread_stream(stream, SIZE_MAX));\
                if (stream->ptr)\
@@ -30,19 +35,18 @@ static void (*outconv)(double x, double y, double z, double 
a);
 
 #define OUTCONV(TYPE)\
        do {\
-               TYPE pixel[4];\
-               pixel[0] = (TYPE)x;\
-               pixel[1] = (TYPE)y;\
-               pixel[2] = (TYPE)z;\
-               pixel[3] = (TYPE)a;\
-               ewriteall(STDOUT_FILENO, pixel, sizeof(pixel), "<stdout>");\
+               TYPE *out = alloca(n * 4 * sizeof(TYPE));\
+               size_t i, m = n * 4;\
+               for (i = 0; i < m; i++)\
+                       out[i] = (TYPE)(xyzas[i]);\
+               ewriteall(STDOUT_FILENO, out, n * 4 * sizeof(TYPE), 
"<stdout>");\
        } while (0)
 
 static void inconv_xyza (struct stream *stream) {INCONV(double);}
 static void inconv_xyzaf(struct stream *stream) {INCONV(float);}
 
-static void outconv_xyza (double x, double y, double z, double a) 
{OUTCONV(double);}
-static void outconv_xyzaf(double x, double y, double z, double a) 
{OUTCONV(float);}
+static void outconv_xyza (double *xyzas, size_t n) {OUTCONV(double);}
+static void outconv_xyzaf(double *xyzas, size_t n) {OUTCONV(float);}
 
 int
 main(int argc, char *argv[])