-#if CHAN_BITS == 8
-
-#define BYTE_TO_CHAN(b) ((b) < 0 ? 0 : (GLchan) (b))
-#define UBYTE_TO_CHAN(b) (b)
-#define SHORT_TO_CHAN(s) ((s) < 0 ? 0 : (GLchan) ((s) >> 7))
-#define USHORT_TO_CHAN(s) ((GLchan) ((s) >> 8))
-#define INT_TO_CHAN(i) ((i) < 0 ? 0 : (GLchan) ((i) >> 23))
-#define UINT_TO_CHAN(i) ((GLchan) ((i) >> 24))
-
-#define CHAN_TO_UBYTE(c) (c)
-#define CHAN_TO_FLOAT(c) UBYTE_TO_FLOAT(c)
-
-#define CLAMPED_FLOAT_TO_CHAN(c, f) CLAMPED_FLOAT_TO_UBYTE(c, f)
-#define UNCLAMPED_FLOAT_TO_CHAN(c, f) UNCLAMPED_FLOAT_TO_UBYTE(c, f)
-
-#define COPY_CHAN4(DST, SRC) COPY_4UBV(DST, SRC)
-
-#define CHAN_PRODUCT(a, b) ((GLubyte) (((GLint)(a) * ((GLint)(b) + 1)) >> 8))
-
-
-#elif CHAN_BITS == 16
-
-#define BYTE_TO_CHAN(b) ((b) < 0 ? 0 : (((GLchan) (b)) * 516))
-#define UBYTE_TO_CHAN(b) ((((GLchan) (b)) << 8) | ((GLchan) (b)))
-#define SHORT_TO_CHAN(s) ((s) < 0 ? 0 : (GLchan) (s))
-#define USHORT_TO_CHAN(s) (s)
-#define INT_TO_CHAN(i) ((i) < 0 ? 0 : (GLchan) ((i) >> 15))
-#define UINT_TO_CHAN(i) ((GLchan) ((i) >> 16))
-
-#define CHAN_TO_UBYTE(c) ((c) >> 8)
-#define CHAN_TO_FLOAT(c) ((GLfloat) ((c) * (1.0 / CHAN_MAXF)))
-
-#define CLAMPED_FLOAT_TO_CHAN(c, f) CLAMPED_FLOAT_TO_USHORT(c, f)
-#define UNCLAMPED_FLOAT_TO_CHAN(c, f) UNCLAMPED_FLOAT_TO_USHORT(c, f)
-
-#define COPY_CHAN4(DST, SRC) COPY_4V(DST, SRC)
-
-#define CHAN_PRODUCT(a, b) ((GLchan) ((((GLuint) (a)) * ((GLuint) (b))) / 65535))
-
-
-#elif CHAN_BITS == 32
-
-/* XXX floating-point color channels not fully thought-out */
-#define BYTE_TO_CHAN(b) ((GLfloat) ((b) * (1.0F / 127.0F)))
-#define UBYTE_TO_CHAN(b) ((GLfloat) ((b) * (1.0F / 255.0F)))
-#define SHORT_TO_CHAN(s) ((GLfloat) ((s) * (1.0F / 32767.0F)))
-#define USHORT_TO_CHAN(s) ((GLfloat) ((s) * (1.0F / 65535.0F)))
-#define INT_TO_CHAN(i) ((GLfloat) ((i) * (1.0F / 2147483647.0F)))
-#define UINT_TO_CHAN(i) ((GLfloat) ((i) * (1.0F / 4294967295.0F)))
-
-#define CHAN_TO_UBYTE(c) FLOAT_TO_UBYTE(c)
-#define CHAN_TO_FLOAT(c) (c)
-
-#define CLAMPED_FLOAT_TO_CHAN(c, f) c = (f)
-#define UNCLAMPED_FLOAT_TO_CHAN(c, f) c = (f)
-
-#define COPY_CHAN4(DST, SRC) COPY_4V(DST, SRC)
-
-#define CHAN_PRODUCT(a, b) ((a) * (b))
-
-#else
-
-#error unexpected CHAN_BITS size
-
-#endif
-
-
-
-/*
- * Convert 3 channels at once.