Avoid always rebuilding: cache when deps are found.

Author: schmonz

GNUmakefile

@@ -14,8 +14,9 @@ GD_LIBS		:= $(shell pkg-config --libs gdlib 2>/dev/null)
 IMAGEMAGICK	:= $(shell compare 2>/dev/null | grep ImageMagick)
 IMLIB2_CFLAGS	:= $(shell pkg-config --cflags imlib2 2>/dev/null)
 IMLIB2_LIBS	:= $(shell pkg-config --libs imlib2 2>/dev/null)
-
-BUILD_WITH_MPC	?= no
+MPC		:= $(shell cpp -dM ${GD_CFLAGS} -include mpc.h </dev/null 2>/dev/null | grep MPC_VERSION_STRING)
+MPC_CFLAGS	= ${GD_CFLAGS}
+MPC_LIBS	=  -lmpc -lmpfr -lgmp
 
 SILENT		=  @
 
@@ -24,57 +25,69 @@ all: check approval
 check: ${THE_TESTS}
 	${SILENT}./${THE_TESTS}
 
-approval: is-imagemagick-installed ${THE_PROGRAM}
+approval: .has_imagemagick ${THE_PROGRAM}
 	${SILENT}./${THE_PROGRAM} gd pngelbrot.png 800 500 100 0.0 0.0 4.0
 	${SILENT}./${APPROVAL_TESTS} pngelbrot.png
 
 valgrind: ${THE_TESTS}
 	${SILENT}valgrind --leak-check=full --show-leak-kinds=all ./${THE_TESTS}
 
 clean:
-	${SILENT}rm -f *.o ${THE_TESTS} ${THE_LIBRARY} ${THE_PROGRAM}
+	${SILENT}rm -f .has_* *.o ${THE_TESTS} ${THE_LIBRARY} ${THE_PROGRAM}
 	${SILENT}rm -rf *.dSYM
 
-is-cairo-installed:
+.PHONY: all check approval valgrind clean
+
+.has_cairo:
 ifeq (, ${CAIRO_LIBS})
 	${SILENT}echo "Please install Cairo (https://www.cairographics.org)." && false
+else
+	${SILENT}touch .has_cairo
 endif
 
-is-check-installed:
+.has_check:
 ifeq (, ${CHECK_LIBS})
 	${SILENT}echo "Please install Check (https://libcheck.github.io/check/)." && false
+else
+	${SILENT}touch .has_check
 endif
 
-is-gd-installed:
+.has_gd:
 ifeq (, ${GD_LIBS})
 	${SILENT}echo "Please install GD (http://libgd.github.io)." && false
+else
+	${SILENT}touch .has_gd
 endif
 
-is-imagemagick-installed:
+.has_imagemagick:
 ifeq (, ${IMAGEMAGICK})
 	${SILENT}echo "Please install ImageMagick (http://www.imagemagick.org)." && false
+else
+	${SILENT}touch .has_imagemagick
 endif
 
-is-imlib2-installed:
+.has_imlib2:
 ifeq (, ${IMLIB2_LIBS})
 	${SILENT}echo "Please install Imlib 2 (http://docs.enlightenment.org/api/imlib2/html/)." && false
+else
+	${SILENT}touch .has_imlib2
 endif
 
-is-mpc-installed:
-ifeq (yes, ${BUILD_WITH_MPC}) # XXX a little too phony
-MPC_CFLAGS	=  -DUSE_MPC ${GD_CFLAGS}
-MPC_LIBS	=  -lmpc -lmpfr -lgmp
+.has_mpc:
+ifeq (, ${MPC})
+	${SILENT}echo "Please install GNU MPC (http://www.multiprecision.org)." && false
+else
+	${SILENT}touch .has_mpc
 endif
 
-.PHONY: all check approval valgrind clean is-cairo-installed is-check-installed is-gd-installed is-imagemagick-installed is-imlib2-installed is-mpc-installed
-
-${THE_TESTS}: is-check-installed ${THE_LIBRARY} check_mandelbrot.c
+${THE_TESTS}: .has_check ${THE_LIBRARY} check_mandelbrot.c
 	${SILENT}${CC} ${CFLAGS} ${CHECK_CFLAGS} -o ${THE_TESTS} check_mandelbrot.c ${THE_LIBRARY} ${LIBS} ${CAIRO_LIBS} ${GD_LIBS} ${IMLIB2_LIBS} ${MPC_LIBS} ${CHECK_LIBS}
 
-${THE_LIBRARY}: is-cairo-installed is-gd-installed is-imlib2-installed is-mpc-installed graph_cairo.h graph_gd.h graph_imlib2.h graph.h graph.c mandelbrot.h mandelbrot.c
+${THE_LIBRARY}: .has_cairo .has_gd .has_imlib2 .has_mpc graph_cairo.h graph_gd.h graph_imlib2.h graph.h graph.c mandelbrot.h mandelbrot.c mandelbrot_mpc.c
 	${SILENT}${CC} ${CFLAGS} ${CAIRO_CFLAGS} ${GD_CFLAGS} ${IMLIB2_CFLAGS} -c graph.c
-	${SILENT}${CC} ${CFLAGS} ${MPC_CFLAGS} -c mandelbrot.c
-	${SILENT}ar rc ${THE_LIBRARY} graph.o mandelbrot.o
+	${SILENT}${CC} ${CFLAGS} -c mandelbrot.c
+	${SILENT}${CC} ${CFLAGS} ${MPC_CFLAGS} -c mandelbrot_mpc.c
+	${SILENT}ar rc ${THE_LIBRARY} graph.o mandelbrot.o mandelbrot_mpc.o
 	${SILENT}ranlib ${THE_LIBRARY}
 
 ${THE_PROGRAM}: ${THE_LIBRARY} mandelbrot.h main.c

README.md

@@ -12,7 +12,6 @@ Now I'm drawing it in C:
 
 ## TODO
 
-7. Why does the code always get rebuilt?
 7. Improve safety and style of `graph_t.image` declaration.
 7. Why did Cairo get slower with this refactoring? Where are we spending our time?
 7. Choose colormap size at runtime.

mandelbrot.c

@@ -1,10 +1,6 @@
 #include <complex.h>
 #include <stdlib.h>
 
-#ifdef USE_MPC
-#include <mpc.h>
-#endif
-
 #include "graph.h"
 #include "mandelbrot.h"
 
@@ -13,34 +9,6 @@ choose_escape_color(const complex double c, const size_t maximum_iterations)
 {
     size_t escape = 0;
 
-#ifdef USE_MPC
-    const mpfr_prec_t precision = 53;
-    mpc_rnd_t rounding_mode = MPC_RNDNN;
-
-    mpc_t my_z, my_temp, my_c;
-    mpfr_t my_mpfr_absolute_value;
-    mpc_init2(my_z, precision), mpc_init2(my_temp, precision),
-        mpc_init2(my_c, precision);
-    mpfr_init2(my_mpfr_absolute_value, precision);
-
-    mpc_set_dc(my_c, c, rounding_mode);
-    mpc_set_dc(my_z, 0.0 + I * 0.0, rounding_mode);
-
-    for (; escape < maximum_iterations; escape++) {
-        mpc_pow_d(my_temp, my_z, 2.0, rounding_mode);
-
-        mpc_abs(my_mpfr_absolute_value, my_temp, rounding_mode);
-        if (mpfr_get_d(my_mpfr_absolute_value, rounding_mode) > 2)
-            break;
-
-        mpc_add(my_z, my_temp, my_c, rounding_mode);
-    }
-
-    mpfr_clear(my_mpfr_absolute_value);
-    mpc_clear(my_c);
-    mpc_clear(my_temp);
-    mpc_clear(my_z);
-#else
     complex double z = 0.0 + I * 0.0;
     complex double temp;
 
@@ -52,7 +20,6 @@ choose_escape_color(const complex double c, const size_t maximum_iterations)
 
         z = temp + c;
     }
-#endif /* USE_MPC */
 
     if (escape == maximum_iterations)
         escape = 0;

mandelbrot_mpc.c

@@ -0,0 +1,51 @@
+#include <complex.h>
+#include <stdlib.h>
+
+#include <mpc.h>
+
+size_t
+choose_escape_color_mpc(const complex double c, const size_t maximum_iterations)
+{
+    size_t escape = 0;
+
+    const mpfr_prec_t precision = 53;
+    mpc_rnd_t rounding_mode = MPC_RNDNN;
+
+    mpc_t my_z, my_temp, my_c;
+    mpfr_t my_mpfr_absolute_value;
+    mpc_init2(my_z, precision), mpc_init2(my_temp, precision),
+        mpc_init2(my_c, precision);
+    mpfr_init2(my_mpfr_absolute_value, precision);
+
+    mpc_set_dc(my_c, c, rounding_mode);
+    mpc_set_dc(my_z, 0.0 + I * 0.0, rounding_mode);
+
+    for (; escape < maximum_iterations; escape++) {
+        mpc_pow_d(my_temp, my_z, 2.0, rounding_mode);
+
+        mpc_abs(my_mpfr_absolute_value, my_temp, rounding_mode);
+        if (mpfr_get_d(my_mpfr_absolute_value, rounding_mode) > 2)
+            break;
+
+        mpc_add(my_z, my_temp, my_c, rounding_mode);
+    }
+
+    mpfr_clear(my_mpfr_absolute_value);
+    mpc_clear(my_c);
+    mpc_clear(my_temp);
+    mpc_clear(my_z);
+
+    if (escape == maximum_iterations)
+        escape = 0;
+
+    if (escape == 0)
+        return 0;
+    else if (escape <= (maximum_iterations / 7))
+        return 1;
+    else if (escape <= (maximum_iterations / 5))
+        return 2;
+    else
+        return 3;
+
+    return escape;
+}