ref: c3938067180ed707828cdbcd0b2d430a13323dd9
dir: /sys/src/libdraw/chan.c/
#include <u.h> #include <libc.h> #include <draw.h> static char channames[] = "rgbkamx"; char* chantostr(char *buf, ulong cc) { ulong c, rc; char *p; if(chantodepth(cc) == 0) return nil; /* reverse the channel descriptor so we can easily generate the string in the right order */ rc = 0; for(c=cc; c; c>>=8){ rc <<= 8; rc |= c&0xFF; } p = buf; for(c=rc; c; c>>=8) { *p++ = channames[TYPE(c)]; *p++ = '0'+NBITS(c); } *p = 0; return buf; } /* avoid pulling in ctype when using with drawterm etc. */ static int isspace(char c) { return c==' ' || c== '\t' || c=='\r' || c=='\n'; } ulong strtochan(char *s) { char *p, *q; ulong c; int t, n, d; c = 0; d = 0; p=s; while(*p && isspace(*p)) p++; while(*p && !isspace(*p)){ if((q = strchr(channames, p[0])) == nil) return 0; t = q-channames; if(p[1] < '0' || p[1] > '9') return 0; n = p[1]-'0'; d += n; c = (c<<8) | __DC(t, n); p += 2; } if(d==0 || (d>8 && d%8) || (d<8 && 8%d)) return 0; return c; } int chantodepth(ulong c) { int n; for(n=0; c; c>>=8){ if(TYPE(c) >= NChan || NBITS(c) > 8 || NBITS(c) <= 0) return 0; n += NBITS(c); } if(n==0 || (n>8 && n%8) || (n<8 && 8%n)) return 0; return n; }