Move histogram calculation to a separate file

Makefile

@@ -11,7 +11,7 @@ OBJS = $(addsuffix .o,${BINS})
 .PHONY: all
 all: $(OUT_DIR) ${BINS}
 
-${BINS}: %: $(OUT_DIR)/png_wrapper.o %.o
+${BINS}: %: $(OUT_DIR)/png_wrapper.o $(OUT_DIR)/histogram.o %.o
 	$(CC) -o $@ $^ -L $(LDIR) $(LIBS)
 
 .SECONDEXPANSION:
@@ -21,6 +21,9 @@ ${OBJS}: $(OUT_DIR)/%.o: %/$$*.c
 $(OUT_DIR)/png_wrapper.o: png_wrapper.c
 	$(CC) -c -o $@ $< -I . -I $(IDIR) $(CFLAGS)
 
+$(OUT_DIR)/histogram.o: histogram.c
+	$(CC) -c -o $@ $< -I . -I $(IDIR) $(CFLAGS)
+
 $(OUT_DIR):
 	mkdir -p $(OUT_DIR)
 

histogram.c

@@ -0,0 +1,34 @@
+#include "histogram.h"
+
+void histogram(struct Image in, struct Image out)
+{
+	size_t pixels_count[MAX_COLOR + 1] = { };
+
+	for (size_t y = 0; y < in.height; y++)
+		for (size_t x = 0; x < in.width; x++)
+			pixels_count[in.pixels[y][x]]++;
+
+	size_t max_count = 0;
+	for (size_t c = 0; c <= MAX_COLOR; c++)
+		if (pixels_count[c] > max_count)
+			max_count = pixels_count[c];
+
+	double k = HIST_HEIGHT / (double) max_count;
+
+	for (size_t y = 0; y < HIST_HEIGHT; y++)
+		for (size_t x = 0; x < HIST_WIDTH; x++)
+			out.pixels[y][x] = 0;
+
+	for (size_t c = 0; c <= MAX_COLOR; c++)
+	{
+		size_t x = c * 2;
+		size_t h = pixels_count[c] * k + 0.5;
+		if (h > HIST_HEIGHT) h = HIST_HEIGHT;
+
+		for (size_t y = 0; y < h; y++)
+		{
+			out.pixels[HIST_HEIGHT - y - 1][x] = 255;
+			out.pixels[HIST_HEIGHT - y - 1][x + 1] = 222;
+		}
+	}
+}

histogram.h

@@ -0,0 +1,11 @@
+#ifndef HISTOGRAM_H
+#define HISTOGRAM_H
+
+#include <stdlib.h>
+#include "png_wrapper.h"
+
+enum { HIST_WIDTH = 512, HIST_HEIGHT = 256, MAX_COLOR = 255 };
+
+void histogram(struct Image in, struct Image out);
+
+#endif

lab4/lab4.c

@@ -1,40 +1,6 @@
 #include <stdlib.h>
 #include "png_wrapper.h"
-
-enum { HIST_WIDTH = 512, HIST_HEIGHT = 256, MAX_COLOR = 255 };
-
-static void histogram(struct Image in, struct Image out)
-{
-	size_t pixels_count[MAX_COLOR + 1] = { };
-
-	for (size_t y = 0; y < in.height; y++)
-		for (size_t x = 0; x < in.width; x++)
-			pixels_count[in.pixels[y][x]]++;
-
-	size_t max_count = 0;
-	for (size_t c = 0; c <= MAX_COLOR; c++)
-		if (pixels_count[c] > max_count)
-			max_count = pixels_count[c];
-
-	double k = HIST_HEIGHT / (double) max_count;
-
-	for (size_t y = 0; y < HIST_HEIGHT; y++)
-		for (size_t x = 0; x < HIST_WIDTH; x++)
-			out.pixels[y][x] = 0;
-
-	for (size_t c = 0; c <= MAX_COLOR; c++)
-	{
-		size_t x = c * 2;
-		size_t h = pixels_count[c] * k + 0.5;
-		if (h > HIST_HEIGHT) h = HIST_HEIGHT;
-
-		for (size_t y = 0; y < h; y++)
-		{
-			out.pixels[HIST_HEIGHT - y - 1][x] = 255;
-			out.pixels[HIST_HEIGHT - y - 1][x + 1] = 222;
-		}
-	}
-}
+#include "histogram.h"
 
 void precalculate(unsigned char *lut, size_t s1, size_t s2)
 {