Add support for absolute transform

src/sfloader/fluid_defsfont.c

@@ -1639,7 +1639,7 @@ fluid_zone_mod_import_sfont(char *zone_name, fluid_mod_t **mod, SFZone *sfzone)
         /* Note: When secondary source input (src2) is set to General Controller 'No Controller',
            output will be forced to +1.0 at synthesis time (see fluid_mod_get_value()).
            That means that this source will behave unipolar only. We need to force the
-           unipolar flag to ensure to ensure a correct evaluation of the minimum
+           unipolar flag to ensure a correct evaluation of the minimum
            value later (see fluid_voice_get_lower_boundary_for_attenuation()).
         */
         if(((mod_dest->flags2 & FLUID_MOD_CC) == FLUID_MOD_GC) && 
@@ -1648,14 +1648,8 @@ fluid_zone_mod_import_sfont(char *zone_name, fluid_mod_t **mod, SFZone *sfzone)
             mod_dest->flags2 &= ~FLUID_MOD_BIPOLAR;
         }
 
-        /* *** Transform *** */
-        /* SF2.01 only uses the 'linear' transform (0).
-         * Deactivate the modulator by setting the amount to 0 in any other case.
-         */
-        if(mod_src->trans != 0)
-        {
-            mod_dest->amount = 0;
-        }
+        /* *** Transform Type *** */
+        mod_dest->trans = mod_src->trans;
 
         /* Store the new modulator in the zone The order of modulators
          * will make a difference, at least in an instrument context: The

src/synth/fluid_mod.c

@@ -39,6 +39,7 @@ fluid_mod_clone(fluid_mod_t *mod, const fluid_mod_t *src)
     mod->src2 = src->src2;
     mod->flags2 = src->flags2;
     mod->amount = src->amount;
+    mod->trans = src->trans;
 }
 
 /**
@@ -382,6 +383,7 @@ fluid_mod_get_value(fluid_mod_t *mod, fluid_voice_t *voice)
     extern fluid_mod_t default_vel2filter_mod;
 
     fluid_real_t v1 = 0.0, v2 = 1.0;
+    fluid_real_t final_value;
     /* The wording of the default modulators refers to a range of 127/128.
      * And the table in section 9.5.3 suggests, that this mapping should be applied
      * to all unipolar and bipolar mappings respectively.
@@ -470,8 +472,14 @@ fluid_mod_get_value(fluid_mod_t *mod, fluid_voice_t *voice)
         v2 = 1.0f;
     }
 
-    /* it's as simple as that: */
-    return (fluid_real_t) mod->amount * v1 * v2;
+    /* it indeed is as simple as that: */
+    final_value = (fluid_real_t) mod->amount * v1 * v2;
+    /* check for absolute value transform*/
+    if(mod->trans == 2)
+    {
+        final_value = fabs(final_value);
+    }
+    return final_value;
 }
 
 /**

src/synth/fluid_mod.h

@@ -34,6 +34,7 @@ struct _fluid_mod_t
     unsigned char flags1;         /**< Source controller 1 flags */
     unsigned char src2;           /**< Source controller 2 */
     unsigned char flags2;         /**< Source controller 2 flags */
+    unsigned char trans;          /**< Output transform flag */
     double amount;                /**< Multiplier amount */
     /* The 'next' field allows to link modulators into a list.  It is
      * not used in fluid_voice.c, there each voice allocates memory for a