我想在C语言中将ASCII string
转换为TBCD(Telephony Binary-Coded Decimal)
格式,反之亦然。我搜索了许多站点,但找不到答案。
最佳答案
最简单的方法可能是使用一对数组将每个ASCII字符映射到对应的TBCD。反之亦然。
在what I read on Wikipedia中,您应该使用以下命令:
const char *tbcd_to_ascii = "0123456789*#abc";
const char ascii_to_tbcd[] = {
15, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* filler when there is an odd number of digits */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0,11, 0, 0, 0, 0, 0, 0,10, 0, 0, 0, 0, 0, /* # * */
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0 /* digits */
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0,12,13,14 /* a b c */
};
如果您有TBCD,要将其转换为ASCII,则可以执行以下操作:
/* The TBCD to convert */
int tbcd[] = { 0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe };
/* The converted ASCII string will be stored here. Make sure to have
enough room for the result and a terminating 0 */
char ascii[16] = { 0 };
/* Convert the TBCD to ASCII */
int i;
for (i = 0; i < sizeof(tbcd)/sizeof(*tbcd); i++) {
ascii[2 * i] = tbcd_to_ascii[tbcd[i] & 0x0f];
ascii[2 * i + 1] = tbcd_to_ascii[(tbcd[i] & 0xf0) >> 4];
}
要将ASCII转换为TBCD,请执行以下操作:
/* ASCII number */
const char *ascii = "0123456789*#abc";
/* The converted TBCD number will be stored here. Make sure to have enough room for the result */
int tbcd[8];
int i;
int len = strlen(ascii);
for (i = 0; i < len; i += 2)
tbcd[i / 2] = ascii_to_tbcd[ascii[i]]
| (ascii_to_tbcd[ascii[i + 1]] << 4);
编辑:@Kevin指出TBCD每字节包装两位数字。