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author | rsc <devnull@localhost> | 2004-04-19 19:29:25 +0000 |
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committer | rsc <devnull@localhost> | 2004-04-19 19:29:25 +0000 |
commit | a84cbb2a17c9d0b88c561d5b7cb50d79a19e7c46 (patch) | |
tree | 59a0e921597e5aa53e83d487c16727a7bf01547a /src/libmach/ieee.c | |
parent | 0e3cc9f456ea49919459bf1164d0c8309a6134fa (diff) | |
download | plan9port-a84cbb2a17c9d0b88c561d5b7cb50d79a19e7c46.tar.gz plan9port-a84cbb2a17c9d0b88c561d5b7cb50d79a19e7c46.tar.bz2 plan9port-a84cbb2a17c9d0b88c561d5b7cb50d79a19e7c46.zip |
libmach
Diffstat (limited to 'src/libmach/ieee.c')
-rw-r--r-- | src/libmach/ieee.c | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/src/libmach/ieee.c b/src/libmach/ieee.c new file mode 100644 index 00000000..0d756d21 --- /dev/null +++ b/src/libmach/ieee.c @@ -0,0 +1,169 @@ +#include <u.h> +#include <libc.h> +#include <bio.h> +#include <mach.h> + +/* + * These routines assume that if the number is representable + * in IEEE floating point, it will be representable in the native + * double format. Naive but workable, probably. + */ +int +ieeeftoa64(char *buf, uint n, u32int h, u32int l) +{ + double fr; + int exp; + + if (n <= 0) + return 0; + + + if(h & (1L<<31)){ + *buf++ = '-'; + h &= ~(1L<<31); + }else + *buf++ = ' '; + n--; + if(l == 0 && h == 0) + return snprint(buf, n, "0."); + exp = (h>>20) & ((1L<<11)-1L); + if(exp == 0) + return snprint(buf, n, "DeN(%.8lux%.8lux)", h, l); + if(exp == ((1L<<11)-1L)){ + if(l==0 && (h&((1L<<20)-1L)) == 0) + return snprint(buf, n, "Inf"); + else + return snprint(buf, n, "NaN(%.8lux%.8lux)", h&((1L<<20)-1L), l); + } + exp -= (1L<<10) - 2L; + fr = l & ((1L<<16)-1L); + fr /= 1L<<16; + fr += (l>>16) & ((1L<<16)-1L); + fr /= 1L<<16; + fr += (h & (1L<<20)-1L) | (1L<<20); + fr /= 1L<<21; + fr = ldexp(fr, exp); + return snprint(buf, n, "%.18g", fr); +} + +int +ieeeftoa32(char *buf, uint n, u32int h) +{ + double fr; + int exp; + + if (n <= 0) + return 0; + + if(h & (1L<<31)){ + *buf++ = '-'; + h &= ~(1L<<31); + }else + *buf++ = ' '; + n--; + if(h == 0) + return snprint(buf, n, "0."); + exp = (h>>23) & ((1L<<8)-1L); + if(exp == 0) + return snprint(buf, n, "DeN(%.8lux)", h); + if(exp == ((1L<<8)-1L)){ + if((h&((1L<<23)-1L)) == 0) + return snprint(buf, n, "Inf"); + else + return snprint(buf, n, "NaN(%.8lux)", h&((1L<<23)-1L)); + } + exp -= (1L<<7) - 2L; + fr = (h & ((1L<<23)-1L)) | (1L<<23); + fr /= 1L<<24; + fr = ldexp(fr, exp); + return snprint(buf, n, "%.9g", fr); +} + +int +beieeeftoa32(char *buf, uint n, void *s) +{ + return ieeeftoa32(buf, n, beswap4(*(u32int*)s)); +} + +int +beieeeftoa64(char *buf, uint n, void *s) +{ + return ieeeftoa64(buf, n, beswap4(*(u32int*)s), beswap4(((u32int*)(s))[1])); +} + +int +leieeeftoa32(char *buf, uint n, void *s) +{ + return ieeeftoa32(buf, n, leswap4(*(u32int*)s)); +} + +int +leieeeftoa64(char *buf, uint n, void *s) +{ + return ieeeftoa64(buf, n, leswap4(((u32int*)(s))[1]), leswap4(*(u32int*)s)); +} + +/* packed in 12 bytes, with s[2]==s[3]==0; mantissa starts at s[4]*/ +int +beieeeftoa80(char *buf, uint n, void *s) +{ + uchar *reg = (uchar*)s; + int i; + ulong x; + uchar ieee[8+8]; /* room for slop */ + uchar *p, *q; + + memset(ieee, 0, sizeof(ieee)); + /* sign */ + if(reg[0] & 0x80) + ieee[0] |= 0x80; + + /* exponent */ + x = ((reg[0]&0x7F)<<8) | reg[1]; + if(x == 0) /* number is ±0 */ + goto done; + if(x == 0x7FFF){ + if(memcmp(reg+4, ieee+1, 8) == 0){ /* infinity */ + x = 2047; + }else{ /* NaN */ + x = 2047; + ieee[7] = 0x1; /* make sure */ + } + ieee[0] |= x>>4; + ieee[1] |= (x&0xF)<<4; + goto done; + } + x -= 0x3FFF; /* exponent bias */ + x += 1023; + if(x >= (1<<11) || ((reg[4]&0x80)==0 && x!=0)) + return snprint(buf, n, "not in range"); + ieee[0] |= x>>4; + ieee[1] |= (x&0xF)<<4; + + /* mantissa */ + p = reg+4; + q = ieee+1; + for(i=0; i<56; i+=8, p++, q++){ /* move one byte */ + x = (p[0]&0x7F) << 1; + if(p[1] & 0x80) + x |= 1; + q[0] |= x>>4; + q[1] |= (x&0xF)<<4; + } + done: + return beieeeftoa64(buf, n, (void*)ieee); +} + + +int +leieeeftoa80(char *buf, uint n, void *s) +{ + int i; + char *cp; + char b[12]; + + cp = (char*) s; + for(i=0; i<12; i++) + b[11-i] = *cp++; + return beieeeftoa80(buf, n, b); +} |