stimuli: remember and update base pointer for stim_redirect

Running a patch twice broke direct MIDI because pointers were updated
relative to the previous copy instead of the original patch. The commit
fixed the problem. The overall ugliness of the process remains, though.

src/compiler/compiler.c

@@ -544,7 +544,7 @@ struct patch *patch_compile_filename(const char *filename,
 struct stimuli *compiler_get_stimulus(struct compiler_sc *sc)
 {
 	if(!sc->p->stim)
-                sc->p->stim = stim_new();
+                sc->p->stim = stim_new(sc->p);
 	return sc->p->stim;
 }
 
@@ -568,7 +568,7 @@ struct patch *patch_copy(struct patch *p)
 		pixbuf_inc_ref(img->pixbuf);
 	}
 	new_patch->stim = stim_get(p->stim);
-	stim_redirect(p->stim, p, new_patch);
+	stim_redirect(p->stim, new_patch);
 	return new_patch;
 }
 

src/renderer/stimuli.c

@@ -10,6 +10,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <sys/types.h>
 
 #include "stimuli.h"
 
@@ -104,13 +105,15 @@ struct stim_regs *stim_add_midi_ctrl(struct stimuli *s, int chan, int ctrl,
 	return &ct->regs;
 }
 
-struct stimuli *stim_new(void)
+struct stimuli *stim_new(const void *target)
 {
 	struct stimuli *s;
 
 	s = calloc(1, sizeof(struct stimuli));
-	if(s)
+	if(s) {
 		s->ref = 1;
+		s->target = target;
+	}
 	return s;
 }
 
@@ -138,10 +141,11 @@ void stim_put(struct stimuli *s)
 	free(s);
 }
 
-void stim_redirect(struct stimuli *s, const void *old, void *new)
+void stim_redirect(struct stimuli *s, void *new)
 {
 	int i, j;
 	struct s_midi_ctrl *ct;
+	ptrdiff_t d = new-s->target;
 
 	if(!s)
 		return;
@@ -153,9 +157,10 @@ void stim_redirect(struct stimuli *s, const void *old, void *new)
 			if (!ct)
 				continue;
 			if(ct->regs.pfv)
-				ct->regs.pfv = new+((void *) ct->regs.pfv-old);
+				ct->regs.pfv = (void *) ct->regs.pfv+d;
 			if(ct->regs.pvv)
-				ct->regs.pvv = new+((void *) ct->regs.pvv-old);
+				ct->regs.pvv = (void *) ct->regs.pvv+d;
 		}
 	}
+	s->target = new;
 }

src/renderer/stimuli.h

@@ -34,6 +34,7 @@ struct s_midi_chan {
 struct stimuli {
 	struct s_midi_chan *midi[MIDI_CHANS];
 	int ref;
+	const void *target;	/* reference address for pointer relocation */
 };
 
 
@@ -48,9 +49,9 @@ void midi_proc_accel_linear(struct s_midi_ctrl *ct, int value);
 void stim_midi_ctrl(struct stimuli *s, int chan, int ctrl, int value);
 struct stim_regs *stim_add_midi_ctrl(struct stimuli *s, int chan, int ctrl,
     void (*proc)(struct s_midi_ctrl *ct, int value));
-struct stimuli *stim_new(void);
+struct stimuli *stim_new(const void *target);
 struct stimuli *stim_get(struct stimuli *s);
 void stim_put(struct stimuli *s);
-void stim_redirect(struct stimuli *s, const void *old, void *new);
+void stim_redirect(struct stimuli *s, void *new);
 
 #endif /* STIMULI_H */