Support binary and octal floating-point
For consistency, support binary and octal floating-point, and accept a "0d" or "0t" prefix for decimal floating-point. However, we do not accept a binary exponent (p) for a decimal mantissa, or vice versa.
This commit is contained in:
H. Peter Anvin
parent
bea0bbb62c
commit
c65a2f634b
3 changed files with 73 additions and 26 deletions
78
float.c
78
float.c
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@ -424,29 +424,33 @@ static bool ieee_round(int sign, uint16_t * mant, int32_t i)
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return false;
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}
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static int hexval(char c)
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/* Returns a value >= 16 if not a valid hex digit */
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static unsigned int hexval(char c)
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{
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if (c >= '0' && c <= '9')
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return c - '0';
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else if (c >= 'a' && c <= 'f')
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return c - 'a' + 10;
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unsigned int v = (unsigned char) c;
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if (v >= '0' && v <= '9')
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return v - '0';
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else
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return c - 'A' + 10;
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return (v|0x20) - 'a' + 10;
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}
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static bool ieee_flconvert_hex(const char *string, uint16_t * mant,
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int32_t * exponent)
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/* Handle floating-point numbers with radix 2^bits and binary exponent */
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static bool ieee_flconvert_bin(const char *string, int bits,
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uint16_t * mant, int32_t * exponent)
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{
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static const int log2tbl[16] =
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{ -1, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3 };
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uint16_t mult[MANT_WORDS + 1], *mp;
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int ms;
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int32_t twopwr;
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int seendot, seendigit;
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bool seendot, seendigit;
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unsigned char c;
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int radix = 1 << bits;
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unsigned int v;
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twopwr = 0;
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seendot = seendigit = 0;
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seendot = seendigit = false;
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ms = 0;
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mp = NULL;
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@ -461,17 +465,15 @@ static bool ieee_flconvert_hex(const char *string, uint16_t * mant,
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"too many periods in floating-point constant");
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return false;
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}
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} else if (isxdigit(c)) {
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int v = hexval(c);
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} else if ((v = hexval(c)) < (unsigned int)radix) {
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if (!seendigit && v) {
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int l = log2tbl[v];
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seendigit = 1;
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mp = mult;
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ms = 15 - l;
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ms = 15-l;
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twopwr = seendot ? twopwr - 4 + l : l - 3;
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twopwr = seendot ? twopwr-bits+l : l+1-bits;
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}
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if (seendigit) {
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@ -483,13 +485,13 @@ static bool ieee_flconvert_hex(const char *string, uint16_t * mant,
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ms += 16;
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}
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*mp |= v << ms;
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ms -= 4;
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ms -= bits;
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if (!seendot)
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twopwr += 4;
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twopwr += bits;
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} else {
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if (seendot)
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twopwr -= 4;
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twopwr -= bits;
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}
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} else if (c == 'p' || c == 'P') {
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int32_t e;
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@ -656,13 +658,41 @@ static int to_float(const char *str, int sign, uint8_t * result,
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break;
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}
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} else {
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if (str[0] == '0' &&
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(str[1] == 'x' || str[1] == 'X' || str[1] == 'h' || str[1] == 'H'))
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ok = ieee_flconvert_hex(str + 2, mant, &exponent);
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else if (str[0] == '$')
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ok = ieee_flconvert_hex(str + 1, mant, &exponent);
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else
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if (str[0] == '0') {
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switch (str[1]) {
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case 'x': case 'X':
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case 'h': case 'H':
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ok = ieee_flconvert_bin(str+2, 4, mant, &exponent);
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break;
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case 'o': case 'O':
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case 'q': case 'Q':
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ok = ieee_flconvert_bin(str+2, 3, mant, &exponent);
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break;
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case 'b': case 'B':
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case 'y': case 'Y':
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ok = ieee_flconvert_bin(str+2, 1, mant, &exponent);
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break;
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case 'd': case 'D':
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case 't': case 'T':
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ok = ieee_flconvert(str+2, mant, &exponent);
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break;
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case '0': case '1': case '2': case '3': case '4':
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case '5': case '6': case '7': case '8': case '9':
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case '\0':
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/* Leading zero was just a zero */
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ok = ieee_flconvert(str, mant, &exponent);
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break;
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default:
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error(ERR_NONFATAL,
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"floating-point constant: invalid radix `%c'", str[1]);
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ok = false;
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break;
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}
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} else if (str[0] == '$') {
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ok = ieee_flconvert_bin(str+1, 4, mant, &exponent);
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} else {
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ok = ieee_flconvert(str, mant, &exponent);
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}
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if (!ok) {
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type = FL_QNAN;
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@ -141,7 +141,7 @@ int stdscan(void *private_data, struct tokenval *tv)
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}
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} else if (c == 'H' || c == 'h' || c == 'X' || c == 'x') {
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is_hex = true;
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} else if (is_hex && (c == 'P' || c == 'p')) {
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} else if (c == 'P' || c == 'p') {
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is_float = true;
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if (*stdscan_bufptr == '+' || *stdscan_bufptr == '-')
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stdscan_bufptr++;
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@ -1,3 +1,5 @@
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;; Integer constants...
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dd 1010_0101 ; Decimal
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dd 01010_0101 ; Decimal (*not* octal!)
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dd 0d1010_0101 ; Decimal
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@ -20,4 +22,19 @@
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dd 1010_0101h ; Hex
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dd 1010_0101x ; Hex
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dd $1010_0101 ; Hex
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;; Floating-point constants
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;; All of these should output B4A21147
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dd 3.7282705e+4 ; Decimal
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dd 00003.7282705e+4 ; Decimal
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dd 0d3.7282705e+4 ; Decimal
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dd 0t3.7282705e+4 ; Decimal
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dd 0x1.23456789p+15 ; Hex
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dd 0h1.23456789p+15 ; Hex
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dd 0o1.10642547422p+15 ; Octal
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dd 0q1.10642547422p+15 ; Octal
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dd 0b1.0010_0011_0100_0101_0110_0111_1000_1001p+15 ; Binary
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dd 0y1.0010_0011_0100_0101_0110_0111_1000_1001p+15 ; Binary
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