| /* atof_tahoe.c - turn a string into a Tahoe floating point number |
| Copyright 1987, 1993, 2000 Free Software Foundation, Inc. |
| |
| /* This is really a simplified version of atof_vax.c. I glommed it wholesale |
| and then shaved it down. I don't even know how it works. (Don't you find |
| my honesty refreshing? Devon E Bowen <bowen@cs.buffalo.edu> |
| |
| I don't allow uppercase letters in the precision descriptors. |
| i.e. 'f' and 'd' are allowed but 'F' and 'D' aren't. */ |
| |
| #include "as.h" |
| |
| /* Precision in LittleNums. */ |
| #define MAX_PRECISION (4) |
| #define D_PRECISION (4) |
| #define F_PRECISION (2) |
| |
| /* Precision in chars. */ |
| #define D_PRECISION_CHARS (8) |
| #define F_PRECISION_CHARS (4) |
| |
| /* Length in LittleNums of guard bits. */ |
| #define GUARD (2) |
| |
| static const long int mask[] = |
| { |
| 0x00000000, |
| 0x00000001, |
| 0x00000003, |
| 0x00000007, |
| 0x0000000f, |
| 0x0000001f, |
| 0x0000003f, |
| 0x0000007f, |
| 0x000000ff, |
| 0x000001ff, |
| 0x000003ff, |
| 0x000007ff, |
| 0x00000fff, |
| 0x00001fff, |
| 0x00003fff, |
| 0x00007fff, |
| 0x0000ffff, |
| 0x0001ffff, |
| 0x0003ffff, |
| 0x0007ffff, |
| 0x000fffff, |
| 0x001fffff, |
| 0x003fffff, |
| 0x007fffff, |
| 0x00ffffff, |
| 0x01ffffff, |
| 0x03ffffff, |
| 0x07ffffff, |
| 0x0fffffff, |
| 0x1fffffff, |
| 0x3fffffff, |
| 0x7fffffff, |
| 0xffffffff |
| }; |
| |
| /* Shared between flonum_gen2tahoe and next_bits. */ |
| static int bits_left_in_littlenum; |
| static LITTLENUM_TYPE *littlenum_pointer; |
| static LITTLENUM_TYPE *littlenum_end; |
| |
| #if __STDC__ == 1 |
| |
| int flonum_gen2tahoe (int format_letter, FLONUM_TYPE * f, |
| LITTLENUM_TYPE * words); |
| |
| #else /* not __STDC__ */ |
| |
| int flonum_gen2tahoe (); |
| |
| #endif /* not __STDC__ */ |
| |
| static int |
| next_bits (number_of_bits) |
| int number_of_bits; |
| { |
| int return_value; |
| |
| if (littlenum_pointer < littlenum_end) |
| return 0; |
| if (number_of_bits >= bits_left_in_littlenum) |
| { |
| return_value = mask[bits_left_in_littlenum] & *littlenum_pointer; |
| number_of_bits -= bits_left_in_littlenum; |
| return_value <<= number_of_bits; |
| bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits; |
| littlenum_pointer--; |
| if (littlenum_pointer >= littlenum_end) |
| return_value |= ((*littlenum_pointer) >> (bits_left_in_littlenum)) & |
| mask[number_of_bits]; |
| } |
| else |
| { |
| bits_left_in_littlenum -= number_of_bits; |
| return_value = mask[number_of_bits] & |
| ((*littlenum_pointer) >> bits_left_in_littlenum); |
| } |
| return return_value; |
| } |
| |
| static void |
| make_invalid_floating_point_number (words) |
| LITTLENUM_TYPE *words; |
| { |
| /* Floating Reserved Operand Code. */ |
| *words = 0x8000; |
| } |
| |
| static int /* 0 means letter is OK. */ |
| what_kind_of_float (letter, precisionP, exponent_bitsP) |
| /* In: lowercase please. What kind of float? */ |
| char letter; |
| |
| /* Number of 16-bit words in the float. */ |
| int *precisionP; |
| |
| /* Number of exponent bits. */ |
| long int *exponent_bitsP; |
| { |
| int retval; /* 0: OK. */ |
| |
| retval = 0; |
| switch (letter) |
| { |
| case 'f': |
| *precisionP = F_PRECISION; |
| *exponent_bitsP = 8; |
| break; |
| |
| case 'd': |
| *precisionP = D_PRECISION; |
| *exponent_bitsP = 8; |
| break; |
| |
| default: |
| retval = 69; |
| break; |
| } |
| return (retval); |
| } |
| |
| /* Warning: This returns 16-bit LITTLENUMs, because that is what the |
| VAX thinks in. It is up to the caller to figure out any alignment |
| problems and to conspire for the bytes/word to be emitted in the |
| right order. Bigendians beware! */ |
| |
| char * /* Return pointer past text consumed. */ |
| atof_tahoe (str, what_kind, words) |
| char *str; /* Text to convert to binary. */ |
| char what_kind; /* 'd', 'f', 'g', 'h' */ |
| LITTLENUM_TYPE *words; /* Build the binary here. */ |
| { |
| FLONUM_TYPE f; |
| LITTLENUM_TYPE bits[MAX_PRECISION + MAX_PRECISION + GUARD]; |
| /* Extra bits for zeroed low-order bits. */ |
| /* The 1st MAX_PRECISION are zeroed, the last contain flonum bits. */ |
| char *return_value; |
| int precision; /* Number of 16-bit words in the format. */ |
| long int exponent_bits; |
| |
| return_value = str; |
| f.low = bits + MAX_PRECISION; |
| f.high = NULL; |
| f.leader = NULL; |
| f.exponent = NULL; |
| f.sign = '\0'; |
| |
| if (what_kind_of_float (what_kind, &precision, &exponent_bits)) |
| { |
| /* We lost. */ |
| return_value = NULL; |
| make_invalid_floating_point_number (words); |
| } |
| if (return_value) |
| { |
| memset (bits, '\0', sizeof (LITTLENUM_TYPE) * MAX_PRECISION); |
| |
| /* Use more LittleNums than seems necessary: |
| the highest flonum may have 15 leading 0 bits, so could be |
| useless. */ |
| f.high = f.low + precision - 1 + GUARD; |
| |
| if (atof_generic (&return_value, ".", "eE", &f)) |
| { |
| make_invalid_floating_point_number (words); |
| /* We lost. */ |
| return_value = NULL; |
| } |
| else |
| { |
| if (flonum_gen2tahoe (what_kind, &f, words)) |
| return_value = NULL; |
| } |
| } |
| return return_value; |
| } |
| |
| /* In: a flonum, a Tahoe floating point format. |
| Out: a Tahoe floating-point bit pattern. */ |
| |
| int /* 0: OK. */ |
| flonum_gen2tahoe (format_letter, f, words) |
| char format_letter; /* One of 'd' 'f'. */ |
| FLONUM_TYPE *f; |
| LITTLENUM_TYPE *words; /* Deliver answer here. */ |
| { |
| LITTLENUM_TYPE *lp; |
| int precision; |
| long int exponent_bits; |
| int return_value; /* 0 == OK. */ |
| |
| return_value = |
| what_kind_of_float (format_letter, &precision, &exponent_bits); |
| if (return_value != 0) |
| { |
| make_invalid_floating_point_number (words); |
| } |
| else |
| { |
| if (f->low > f->leader) |
| { |
| /* 0.0e0 seen. */ |
| memset (words, '\0', sizeof (LITTLENUM_TYPE) * precision); |
| } |
| else |
| { |
| long int exponent_1; |
| long int exponent_2; |
| long int exponent_3; |
| long int exponent_4; |
| int exponent_skippage; |
| LITTLENUM_TYPE word1; |
| |
| /* JF: Deal with new Nan, +Inf and -Inf codes. */ |
| if (f->sign != '-' && f->sign != '+') |
| { |
| make_invalid_floating_point_number (words); |
| return return_value; |
| } |
| /* All tahoe floating_point formats have: |
| Bit 15 is sign bit. |
| Bits 14:n are excess-whatever exponent. |
| Bits n-1:0 (if any) are most significant bits of fraction. |
| Bits 15:0 of the next word are the next most significant bits. |
| And so on for each other word. |
| |
| So we need: number of bits of exponent, number of bits of |
| mantissa. */ |
| |
| bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS; |
| littlenum_pointer = f->leader; |
| littlenum_end = f->low; |
| |
| /* Seek (and forget) 1st significant bit. */ |
| for (exponent_skippage = 0; |
| !next_bits (1); |
| exponent_skippage++) |
| ; |
| |
| exponent_1 = f->exponent + f->leader + 1 - f->low; |
| |
| /* Radix LITTLENUM_RADIX, point just higher than f -> leader. */ |
| exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS; |
| |
| /* Radix 2. */ |
| exponent_3 = exponent_2 - exponent_skippage; |
| |
| /* Forget leading zeros, forget 1st bit. */ |
| exponent_4 = exponent_3 + (1 << (exponent_bits - 1)); |
| |
| /* Offset exponent. */ |
| |
| if (exponent_4 & ~mask[exponent_bits]) |
| { |
| /* Exponent overflow. Lose immediately. */ |
| |
| make_invalid_floating_point_number (words); |
| |
| /* We leave return_value alone: admit we read the |
| number, but return a floating exception because we |
| can't encode the number. */ |
| } |
| else |
| { |
| lp = words; |
| |
| /* Word 1. Sign, exponent and perhaps high bits. */ |
| /* Assume 2's complement integers. */ |
| word1 = ((exponent_4 & mask[exponent_bits]) |
| << (15 - exponent_bits)) |
| | ((f->sign == '+') ? 0 : 0x8000) |
| | next_bits (15 - exponent_bits); |
| *lp++ = word1; |
| |
| /* The rest of the words are just mantissa bits. */ |
| for (; lp < words + precision; lp++) |
| *lp = next_bits (LITTLENUM_NUMBER_OF_BITS); |
| |
| if (next_bits (1)) |
| { |
| /* Since the NEXT bit is a 1, round UP the mantissa. |
| The cunning design of these hidden-1 floats permits |
| us to let the mantissa overflow into the exponent, and |
| it 'does the right thing'. However, we lose if the |
| highest-order bit of the lowest-order word flips. |
| Is that clear? */ |
| |
| unsigned long int carry; |
| |
| /* #if (sizeof(carry)) < ((sizeof(bits[0]) * |
| BITS_PER_CHAR) + 2) Please allow at least 1 more |
| bit in carry than is in a LITTLENUM. We need |
| that extra bit to hold a carry during a LITTLENUM |
| carry propagation. Another extra bit (kept 0) |
| will assure us that we don't get a sticky sign |
| bit after shifting right, and that permits us to |
| propagate the carry without any masking of bits. |
| #endif */ |
| for (carry = 1, lp--; |
| carry && (lp >= words); |
| lp--) |
| { |
| carry = *lp + carry; |
| *lp = carry; |
| carry >>= LITTLENUM_NUMBER_OF_BITS; |
| } |
| |
| if ((word1 ^ *words) |
| & (1 << (LITTLENUM_NUMBER_OF_BITS - 1))) |
| { |
| make_invalid_floating_point_number (words); |
| /* We leave return_value alone: admit we read |
| the number, but return a floating exception |
| because we can't encode the number. */ |
| } |
| } /* if (we needed to round up) */ |
| } /* if (exponent overflow) */ |
| } /* if (0.0e0) */ |
| } /* if (float_type was OK) */ |
| return return_value; |
| } |
| |
| /* In: input_line_pointer -> the 1st character of a floating-point |
| * number. |
| * 1 letter denoting the type of statement that wants a |
| * binary floating point number returned. |
| * Address of where to build floating point literal. |
| * Assumed to be 'big enough'. |
| * Address of where to return size of literal (in chars). |
| * |
| * Out: Input_line_pointer -> of next char after floating number. |
| * Error message, or 0. |
| * Floating point literal. |
| * Number of chars we used for the literal. */ |
| |
| char * |
| md_atof (what_statement_type, literalP, sizeP) |
| char what_statement_type; |
| char *literalP; |
| int *sizeP; |
| { |
| LITTLENUM_TYPE words[MAX_PRECISION]; |
| register char kind_of_float; |
| register int number_of_chars; |
| register LITTLENUM_TYPE *littlenum_pointer; |
| |
| switch (what_statement_type) |
| { |
| case 'f': /* .ffloat */ |
| case 'd': /* .dfloat */ |
| kind_of_float = what_statement_type; |
| break; |
| |
| default: |
| kind_of_float = 0; |
| break; |
| } |
| |
| if (kind_of_float) |
| { |
| register LITTLENUM_TYPE *limit; |
| |
| input_line_pointer = atof_tahoe (input_line_pointer, |
| kind_of_float, |
| words); |
| /* The atof_tahoe() builds up 16-bit numbers. |
| Since the assembler may not be running on |
| a different-endian machine, be very careful about |
| converting words to chars. */ |
| number_of_chars = (kind_of_float == 'f' ? F_PRECISION_CHARS : |
| (kind_of_float == 'd' ? D_PRECISION_CHARS : 0)); |
| know (number_of_chars <= MAX_PRECISION * sizeof (LITTLENUM_TYPE)); |
| limit = words + (number_of_chars / sizeof (LITTLENUM_TYPE)); |
| for (littlenum_pointer = words; |
| littlenum_pointer < limit; |
| littlenum_pointer++) |
| { |
| md_number_to_chars (literalP, *littlenum_pointer, |
| sizeof (LITTLENUM_TYPE)); |
| literalP += sizeof (LITTLENUM_TYPE); |
| } |
| } |
| else |
| { |
| number_of_chars = 0; |
| } |
| |
| *sizeP = number_of_chars; |
| return kind_of_float ? 0 : _("Bad call to md_atof()"); |
| } |