added gamut table check

check if the gamut table is valid before just blindly accepting it.
make parameters const.

tlc5947/color.c

@@ -119,15 +119,25 @@ rgb12 rgb8torgb12(rgb8 c){
     return _c;
 }
 
-rgb12 rgb12_white_balance(rgb12 c, float m[3]){
+rgb12 rgb12_white_balance(rgb12 c, const float m[3]){
     rgb12 _c;
     _c.r = (uint16_t)(c.r * m[0]);
     _c.g = (uint16_t)(c.g * m[1]);
     _c.b = (uint16_t)(c.b * m[2]);
     return _c;
 }
 
-rgb12 rgb12_gamut(rgb12 c, float m[3][3]){
+
+#define ADD_F(a, b) ((float)(((float)a)+((float)b)))
+#define ADD3_F(a, b, c) ((float)(ADD_F(ADD_F(a, b), ((float)(c)))))
+bool gamut_matrix_valid(const float m[3][3]){
+    for(uint8_t i = 0; i < 3; ++i)
+        if( ADD3_F(m[i][0], m[i][1], m[i][2]) > 1.0 )
+            return false;
+    return true;
+}
+
+rgb12 rgb12_gamut(rgb12 c, const float m[3][3]){
     rgb12 _c;
     _c.r = (uint16_t)((c.r * m[0][0]) + (c.g * m[0][1]) + (c.b * m[0][2]));
     _c.g = (uint16_t)((c.r * m[1][0]) + (c.g * m[1][1]) + (c.b * m[1][2]));

tlc5947/color.h

@@ -32,6 +32,7 @@
 #define TLC5947_COLOR_H
 
 #include <stdint.h>
+#include <stdbool.h>
 
 typedef struct{
     uint16_t r:12; /*< red   [0 -> 4095] */
@@ -74,9 +75,10 @@ rgb8 rgb12torgb8(rgb12 c)__attribute__ ((const));
 
 rgb12 rgb8torgb12(rgb8 c)__attribute__ ((const));
 
-rgb12 rgb12_white_balance(rgb12 c, float m[3]);
+rgb12 rgb12_white_balance(rgb12 c, const float m[3]);
 
-rgb12 rgb12_gamut(rgb12 c, float m[3][3]);
+bool gamut_matrix_valid(const float m[3][3]);
+rgb12 rgb12_gamut(rgb12 c, const float m[3][3]);
 
 #if defined(__cplusplus)
 }

tlc5947/tlc5947.c

@@ -1285,6 +1285,14 @@ STATIC mp_obj_t tlc5947_tlc5947_set_gamut(mp_obj_t self_in, mp_obj_t matrix_in){
             }
         }
     }
+
+    if(!gamut_matrix_valid(self->gamut_m)){
+        memset(self->gamut_m, 0, 9 * sizeof(float));
+        for(uint32_t k = 0; k < 3; k++)
+            self->gamut_m[k][k] = 1.0;
+        mp_raise_ValueError(MP_ERROR_TEXT("invalid matrix"));
+    }
+
     return mp_const_none;
 }