+ /* Check syntax and work out the encoded value (if correct) */
+ if((*p & 0x80) == 0) {
+ value = *p++ & 0x7f;
+ ret = 1;
+ } else if((*p & 0xe0) == 0xc0) {
+ if(len < 2) return -1;
+ if((p[1] & 0xc0) != 0x80) return -3;
+ value = (*p++ & 0x1f) << 6;
+ value |= *p++ & 0x3f;
+ if(value < 0x80) return -4;
+ ret = 2;
+ } else if((*p & 0xf0) == 0xe0) {
+ if(len < 3) return -1;
+ if( ((p[1] & 0xc0) != 0x80)
+ || ((p[2] & 0xc0) != 0x80) ) return -3;
+ value = (*p++ & 0xf) << 12;
+ value |= (*p++ & 0x3f) << 6;
+ value |= *p++ & 0x3f;
+ if(value < 0x800) return -4;
+ ret = 3;
+ } else if((*p & 0xf8) == 0xf0) {
+ if(len < 4) return -1;
+ if( ((p[1] & 0xc0) != 0x80)
+ || ((p[2] & 0xc0) != 0x80)
+ || ((p[3] & 0xc0) != 0x80) ) return -3;
+ value = ((unsigned long)(*p++ & 0x7)) << 18;
+ value |= (*p++ & 0x3f) << 12;
+ value |= (*p++ & 0x3f) << 6;
+ value |= *p++ & 0x3f;
+ if(value < 0x10000) return -4;
+ ret = 4;
+ } else if((*p & 0xfc) == 0xf8) {
+ if(len < 5) return -1;
+ if( ((p[1] & 0xc0) != 0x80)
+ || ((p[2] & 0xc0) != 0x80)
+ || ((p[3] & 0xc0) != 0x80)
+ || ((p[4] & 0xc0) != 0x80) ) return -3;
+ value = ((unsigned long)(*p++ & 0x3)) << 24;
+ value |= ((unsigned long)(*p++ & 0x3f)) << 18;
+ value |= ((unsigned long)(*p++ & 0x3f)) << 12;
+ value |= (*p++ & 0x3f) << 6;
+ value |= *p++ & 0x3f;
+ if(value < 0x200000) return -4;
+ ret = 5;
+ } else if((*p & 0xfe) == 0xfc) {
+ if(len < 6) return -1;
+ if( ((p[1] & 0xc0) != 0x80)
+ || ((p[2] & 0xc0) != 0x80)
+ || ((p[3] & 0xc0) != 0x80)
+ || ((p[4] & 0xc0) != 0x80)
+ || ((p[5] & 0xc0) != 0x80) ) return -3;
+ value = ((unsigned long)(*p++ & 0x1)) << 30;
+ value |= ((unsigned long)(*p++ & 0x3f)) << 24;
+ value |= ((unsigned long)(*p++ & 0x3f)) << 18;
+ value |= ((unsigned long)(*p++ & 0x3f)) << 12;
+ value |= (*p++ & 0x3f) << 6;
+ value |= *p++ & 0x3f;
+ if(value < 0x4000000) return -4;
+ ret = 6;
+ } else return -2;
+ *val = value;
+ return ret;
+}