Index: apps/menus/eq_menu.c
===================================================================
--- apps/menus/eq_menu.c	(revision 30989)
+++ apps/menus/eq_menu.c	(working copy)
@@ -46,6 +46,7 @@
 #include "menu_common.h"
 #include "viewport.h"
 #include "exported_menus.h"
+#include "fixedpoint.h"
 
 /*
  * Utility functions
@@ -378,6 +379,91 @@
     return;
 }
 
+
+void draw_eq_response_graph(long *curve, int x, int y, int width, int height)
+{
+    int h_height = height >> 1;
+    
+    FOR_NB_SCREENS(i) {
+        screens[i].set_drawmode(DRMODE_BG | DRMODE_INVERSEVID);
+        screens[i].fillrect(x, y, width, height);
+        screens[i].set_drawmode(DRMODE_SOLID);
+        int value;
+
+        screens[i].drawrect(x,y,width,height);
+        for (int n=0; n < width-2; n++ ) {
+            value = (long) fp_div( fp_mul(h_height,fp_decibels((1 << 13) + curve[n],13), 13),
+                                   24, 13) >> 13; /* 24dB dynamic range */
+            if (value >= h_height) {
+                value = h_height-1;
+            }
+            if (value <= -h_height) {
+                value = -h_height+1;
+            }
+            screens[i].drawpixel(x+n, y+h_height-value);
+        }
+        
+        screens[i].set_drawmode(DRMODE_COMPLEMENT );
+        long step = fp_div( fp_log10( fp_div(EQ_CUTOFF_MAX<<13, EQ_CUTOFF_MIN<<13, 13), 13), (width-2)<<13 ,13); /* s18.13 */
+        for (int l=0; l<5; l++) {
+            int cutoff = *(&global_settings.eq_band0_cutoff + 3 * l);
+            int c_freq = fp_div( fp_log10( cutoff<<13, 13) - fp_log10(EQ_CUTOFF_MIN<<13, 13), step, 13) >> 13;
+            screens[i].vline( x+c_freq, y+1, y+height+1);
+        }
+        screens[i].set_drawmode(DRMODE_SOLID);
+        //screens[i].update_rect(x, y, width, height);
+
+    }
+}
+
+
+static long* get_filter_response(int band, long *filter_curve, int num_samples)
+{
+    int *filter = &global_settings.eq_band0_gain;
+    filter += 3 * band;
+    long gain = *filter;
+    unsigned long cutoff = *(&global_settings.eq_band0_cutoff + 3 * band);
+    cutoff = cutoff << 13; /* s18.13 */
+    unsigned long q = *(&global_settings.eq_band0_q + 3 * band);
+    const long minfreq = EQ_CUTOFF_MIN<<13;
+    const long sqrtA = fp_exp10(fp_div(gain<<13, 800<<13, 13), 13); /* 10^(db/80), s18.13 */
+    const long A = fp_exp10(fp_div(gain<<13, 400<<13, 13), 13); /* s18.13 */
+    //A = get_replaygain_int(gain*5) >> 11; /* 10^(db/40), s18,13 */
+
+    long step = fp_div( fp_log10( fp_div(EQ_CUTOFF_MAX<<13, EQ_CUTOFF_MIN<<13, 13), 13),
+                        num_samples<<13, 13); /* s18.13 */
+    const long offset = fp_div(fp_log10(minfreq, 13), step, 13);   /* graph starts from minfreq */
+    long s, s2, num, den;
+    int one = 1 << 13;
+    long fp_q = fp_div(q<<13, 10<<13, 13);/* s18.13 */
+    const long A_mul_q = fp_mul(A,fp_q,13);/* s18.13 */
+    const long A_div_q = fp_div(A,fp_q,13);/* s18.13 */
+    const long sqrtA_div_q = fp_div(sqrtA,fp_q,13);/* s18.13 */
+    
+    for (int i=0; i < num_samples; i++){
+        s = fp_div( fp_exp10(fp_mul( (i<<13) + offset,step,13) , 13), cutoff, 13);
+        s2 = fp_mul(s,s,13);
+        if (band == 0 ) {   /* H(s) = A * (s^2 + (sqrt(A)/Q)*s + A)/(A*s^2 + (sqrt(A)/Q)*s + 1) */
+            num = fp_mul(A, (s2 + fp_mul((sqrtA_div_q),s,13) + A),13);
+            den = fp_mul(A,s2,13) + fp_mul((sqrtA_div_q),s,13) + one;
+            filter_curve[i] = fp_div(num,den,13);
+        }
+        else if (band == 4) {   /* H(s) = A * (A*s^2 + (sqrt(A)/Q)*s + 1)/(s^2 + (sqrt(A)/Q)*s + A) */
+            num = fp_mul(A, (fp_mul(A,s2,13) + fp_mul((sqrtA_div_q),s,13) + one),13);
+            den = s2 + fp_mul((sqrtA_div_q),s,13) + A;
+            filter_curve[i] = fp_div(num,den,13);
+        }
+        else {   /* H(s) = (s^2 + s*(A/Q) + 1) / (s^2 + s/(A*Q) + 1)*/
+            filter_curve[i] = fp_div((s2 + fp_mul(s,(A_div_q),13) + one) ,
+                                     (s2 + fp_div(s,(A_mul_q),13) + one),13);
+        }
+        
+    }
+    
+    return filter_curve;
+}
+
+
 /* Provides a graphical means of editing the EQ settings */
 bool eq_menu_graphical(void)
 {
@@ -415,6 +501,29 @@
             nb_eq_sliders[i] = 5;
     }
 
+    int ypos = 120;
+    int xpos = 5;
+
+    int vertsize = screens[0].lcdheight - ypos -5;
+    int horizsize = screens[0].lcdwidth - (xpos << 1);
+    long sum;
+    int i;
+
+    long curves[5][horizsize-2];
+    for (i=0; i<5; i++) {
+        get_filter_response(i, curves[i], horizsize-2);
+    }
+
+    long graph[horizsize-2];
+     
+    for (i=0; i < (horizsize-2); i++) {
+        sum = 0;
+        for (int c=0; c < 5; c++) {
+            sum += curves[c][i] - (1 << 13);
+        }
+        graph[i] = sum;
+    }
+
     y = h + 1;
     
     /* Start off editing gain on the first band */
@@ -489,7 +598,7 @@
             /* Draw equalizer band details */
             draw_eq_sliders(&screens[i], x, y, nb_eq_sliders[i], start_item,
                             current_band, mode);
-
+            draw_eq_response_graph((long*) &graph[0] , xpos, ypos, horizsize, vertsize);
             screens[i].update();
         }
         
@@ -562,6 +671,17 @@
         if (has_changed) {
             dsp_set_eq_coefs(current_band);
             has_changed = false;
+    
+            get_filter_response(current_band, curves[current_band], horizsize-2);
+            for (i=0; i < (horizsize-2); i++) {
+                sum = 0;
+                for (int c=0; c < 5; c++) {
+                    sum += curves[c][i] - (1<<13);
+                }
+                //printf("punto: %i, valore: %i | ", i, curves[current_band][i]);
+                graph[i] = sum;
+            }
+
         }
     }
 
@@ -576,6 +696,7 @@
     return result;
 }
 
+
 static bool eq_save_preset(void)
 {
     /* make sure that the eq is enabled for setting saving */
Index: apps/fixedpoint.c
===================================================================
--- apps/fixedpoint.c	(revision 30989)
+++ apps/fixedpoint.c	(working copy)
@@ -358,7 +358,7 @@
 /** FIXED POINT EXP10
  * Return 10^x as FP integer.  Argument is FP integer.
  */
-static long fp_exp10(long x, unsigned int fracbits)
+long fp_exp10(long x, unsigned int fracbits)
 {
     long k;
     long z;
@@ -413,11 +413,11 @@
 }
 
 
-#if 0   /* useful code, but not currently used */
+
 /** FIXED POINT LOG10
  * Return log10(x) as FP integer.  Argument is FP integer.
  */
-static long fp_log10(long n, unsigned int fracbits)
+long fp_log10(long n, unsigned int fracbits)
 {
     /* Calculate log2 of argument */
 
@@ -465,7 +465,6 @@
     /* decibels = 20 * log10(factor) */
     return FP_MUL_FRAC((20L << fracbits), fp_log10(factor, fracbits));
 }
-#endif  /* unused code */
 
 
 /** CONVERT DECIBELS TO FACTOR */
Index: apps/fixedpoint.h
===================================================================
--- apps/fixedpoint.h	(revision 30989)
+++ apps/fixedpoint.h	(working copy)
@@ -45,13 +45,14 @@
  *          and decibels is a fixed point integer.
  */
 
+
 #ifndef _FIXEDPOINT_H_APPS
 #define _FIXEDPOINT_H_APPS
 
+
 #define fp_mul(x, y, z) (long)((((long long)(x)) * ((long long)(y))) >> (z))
 #define fp_div(x, y, z) (long)((((long long)(x)) << (z)) / ((long long)(y)))
 
-
 /** TAKEN FROM ORIGINAL fixedpoint.h */
 long fp_sincos(unsigned long phase, long *cos);
 
@@ -66,4 +67,10 @@
 /* long fp_decibels(unsigned long factor, unsigned int fracbits); */
 long fp_factor(long decibels, unsigned int fracbits);
 
+long fp_decibels(unsigned long factor, unsigned int fracbits);
+
+long fp_log10(long n, unsigned int fracbits);
+
+long fp_exp10(long n, unsigned int fracbits);
+
 #endif