add channel_palindex and friends

doc/man/man3/notcurses_channels.3.md

@@ -25,11 +25,13 @@ notcurses_channels - operations on notcurses channels
 
 **uint32_t channel_b(uint32_t ***channel***);**
 
-**uint32_t channel_rgb8(uint32_t channel, uint32_t* restrict ***r***, uint32_t* restrict ***g***, uint32_t* restrict ***b***);**
+**uint32_t channel_rgb8(uint32_t ***channel***, uint32_t* restrict ***r***, uint32_t* restrict ***g***, uint32_t* restrict ***b***);**
 
-**int channel_set_rgb8(uint32_t* channel, int ***r***, int ***g***, int ***b***);**
+**unsigned channel_palindex(uint32_t ***channel***);**
 
-**int channel_set(uint32_t* channel, uint32_t rg***b***);**
+**int channel_set_rgb8(uint32_t* ***channel***, int ***r***, int ***g***, int ***b***);**
+
+**int channel_set(uint32_t* ***channel***, uint32_t rg***b***);**
 
 **uint32_t channel_alpha(uint32_t ***channel***);**
 
@@ -55,6 +57,10 @@ notcurses_channels - operations on notcurses channels
 
 **unsigned channels_bg_alpha(uint64_t ***channels***);**
 
+**unsigned channels_fg_palindex(uint64_t ***channels***);**
+
+**unsigned channels_bg_palindex(uint64_t ***channels***);**
+
 **unsigned channels_fg_rgb8(uint64_t ***channels***, unsigned* ***r***, unsigned* ***g***, unsigned* ***b***);**
 
 **unsigned channels_bg_rgb8(uint64_t ***channels***, unsigned* ***r***, unsigned* ***g***, unsigned* ***b***);**

include/notcurses/notcurses.h

@@ -232,6 +232,11 @@ channel_alpha(unsigned channel){
   return channel & CHANNEL_ALPHA_MASK;
 }
 
+static inline unsigned
+channel_palindex(uint32_t channel){
+  return channel & 0xff;
+}
+
 // Set the 2-bit alpha component of the 32-bit channel.
 static inline int
 channel_set_alpha(unsigned* channel, unsigned alpha){
@@ -295,6 +300,16 @@ channels_combine(uint32_t fchan, uint32_t bchan){
   return channels;
 }
 
+static inline unsigned
+channels_fg_palindex(uint64_t channels){
+  return channel_palindex(channels_fchannel(channels));
+}
+
+static inline unsigned
+channels_bg_palindex(uint64_t channels){
+  return channel_palindex(channels_bchannel(channels));
+}
+
 // Extract 24 bits of foreground RGB from 'channels', shifted to LSBs.
 static inline unsigned
 channels_fg_rgb(uint64_t channels){
@@ -1961,7 +1976,7 @@ cell_set_fg_palindex(nccell* cl, int idx){
 
 static inline uint32_t
 cell_fg_palindex(const nccell* cl){
-  return (cl->channels & 0xff00000000ull) >> 32u;
+  return channels_fg_palindex(cl->channels);
 }
 
 // Set the r, g, and b cell for the background component of this 64-bit
@@ -1993,7 +2008,7 @@ cell_set_bg_palindex(nccell* cl, int idx){
 
 static inline uint32_t
 cell_bg_palindex(const nccell* cl){
-  return (cl->channels & 0xff);
+  return channels_bg_palindex(cl->channels);
 }
 
 // Is the foreground using the "default foreground color"?