256-color cube is not ansi, don't muddy the waters

src/lib/internal.h

@@ -168,13 +168,13 @@ flash_damage_map(unsigned char* damage, int count, bool val){
 void ncplane_updamage(ncplane* n);
 
 // For our first attempt, O(1) uniform conversion from 8-bit r/g/b down to
-// ~2.4-bit 6x6x6 ANSI cube + greyscale (assumed on entry; I know no way to
+// ~2.4-bit 6x6x6 cube + greyscale (assumed on entry; I know no way to
 // even semi-portably recover the palette) proceeds via: map each 8-bit to
 // a 5-bit target grey. if all 3 components match, select that grey.
 // otherwise, c / 42.7 to map to 6 values. this never generates pure black
 // nor white, though, lame...FIXME
 static inline int
-rgb_to_ansi256(unsigned r, unsigned g, unsigned b){
+rgb_quantize_256(unsigned r, unsigned g, unsigned b){
   const unsigned GREYMASK = 0xf8;
   // if all 5 MSBs match, return grey from 24-member grey ramp or pure
   // black/white from original 16 (0 and 15, respectively)

src/lib/notcurses.c

@@ -947,7 +947,7 @@ term_bg_rgb8(notcurses* nc, FILE* out, unsigned r, unsigned g, unsigned b){
     // a single screen, start... combining close ones? For 8-color mode, simple
     // interpolation. I have no idea what to do for 88 colors. FIXME
     if(nc->colors >= 256){
-      term_emit("setab", tiparm(nc->setab, rgb_to_ansi256(r, g, b)), out, false);
+      term_emit("setab", tiparm(nc->setab, rgb_quantize_256(r, g, b)), out, false);
     }
     return -1;
   }
@@ -968,7 +968,7 @@ term_fg_rgb8(notcurses* nc, FILE* out, unsigned r, unsigned g, unsigned b){
       return -1;
     }
     if(nc->colors >= 256){
-      term_emit("setaf", tiparm(nc->setaf, rgb_to_ansi256(r, g, b)), out, false);
+      term_emit("setaf", tiparm(nc->setaf, rgb_quantize_256(r, g, b)), out, false);
     }
     // For 256-color indexed mode, start constructing a palette based off
     // the inputs *if we can change the palette*. If more than 256 are used on

tests/internal.cpp

@@ -14,7 +14,7 @@ TEST_F(InternalsTest, RGBtoANSIWhite) {
   unsigned r, g, b;
   for(r = 250 ; r < 256 ; ++r){
     g = b = r;
-    EXPECT_EQ(15, rgb_to_ansi256(r, g, b));
+    EXPECT_EQ(15, rgb_quantize_256(r, g, b));
   }
 }
 
@@ -22,7 +22,7 @@ TEST_F(InternalsTest, RGBtoANSIBlack) {
   unsigned r, g, b;
   for(r = 0 ; r < 10 ; ++r){
     g = b = r;
-    EXPECT_EQ(0, rgb_to_ansi256(r, g, b));
+    EXPECT_EQ(0, rgb_quantize_256(r, g, b));
   }
 }
 
@@ -30,7 +30,7 @@ TEST_F(InternalsTest, RGBtoANSIGrey) {
   unsigned r, g, b;
   for(r = 10 ; r < 244 ; ++r){
     g = b = r;
-    EXPECT_EQ(231 + (r * 5) / 49, rgb_to_ansi256(r, g, b));
+    EXPECT_EQ(231 + (r * 5) / 49, rgb_quantize_256(r, g, b));
   }
 }
 
@@ -39,7 +39,7 @@ TEST_F(InternalsTest, RGBtoANSIRed) {
   unsigned r, g, b;
   g = b = 0x0;
   for(r = 0 ; r < 256 ; ++r){
-    int c256 = rgb_to_ansi256(r, g, b);
+    int c256 = rgb_quantize_256(r, g, b);
     if(r < 8){
       EXPECT_EQ(0, c256);
     }else{
@@ -54,7 +54,7 @@ TEST_F(InternalsTest, RGBtoANSIGreen) {
   unsigned r, g, b;
   r = b = 0x0;
   for(g = 0 ; g < 256 ; ++g){
-    int c256 = rgb_to_ansi256(r, g, b);
+    int c256 = rgb_quantize_256(r, g, b);
     EXPECT_GT(48, c256);
     if(g < 8){
       EXPECT_EQ(0, c256);
@@ -70,7 +70,7 @@ TEST_F(InternalsTest, RGBtoANSIBlue) {
   unsigned r, g, b;
   r = g = 0x0;
   for(b = 0 ; b < 256 ; ++b){
-    int c256 = rgb_to_ansi256(r, g, b);
+    int c256 = rgb_quantize_256(r, g, b);
     EXPECT_GT(22, c256);
     if(b < 8){
       EXPECT_EQ(0, c256);