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libc/printf: Use compiler-provided 64 bit math, phase 2

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Remove the function wrappers around the 64 bit math and just use C
syntax natively, combining ops where appropriate (e.g. there was a
sequence implementing "(x<<2+x)<<2" to do "multiply by 10").  The
_ldiv5 and _rlrshift routines are non-standard ops that provide useful
abstraction, so they remain as separate functions.

Change-Id: I4d83847348fdd7be09887b833c8ccbd2aa1e4182
Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
This commit is contained in:
Andy Ross 2016-08-15 12:50:45 -07:00 • committed by Anas Nashif
commit 5729235b57
1 changed files with 47 additions and 81 deletions
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128
lib/libc/minimal/source/stdout/prf.c
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@ -137,21 +137,8 @@ static int _to_dec(char *buf, int32_t value, int fplus, int fspace, int precisio
return (buf + _to_udec(buf, (uint32_t) value, precision)) - start;
}
static void _llshift(uint32_t value[])
static void _rlrshift(uint64_t *v)
{
*((uint64_t *)&value[0]) <<= 1;
}
static void __attribute__((noinline)) _ladd(uint32_t *result, uint32_t *value)
{
uint64_t *r = (uint64_t *)&result[0];
uint64_t *v = (uint64_t *)&value[0];
*r = *r + *v;
}
static void _rlrshift(uint32_t value[])
{
uint64_t *v = (uint64_t *)&value[0];
*v = (*v & 1) + (*v >> 1);
}
@ -170,9 +157,8 @@ static void _rlrshift(uint32_t value[])
* the input space, and for ~2e12 (4 hours runtime) random inputs
* taken from the full 64 bit space.
*/
static void _ldiv5(uint32_t value[])
static void _ldiv5(uint64_t *v)
{
uint64_t *v = (uint64_t *)&value[0];
uint32_t i, hi;
uint64_t rem = *v, quot = 0, q;
static const char shifts[] = { 32, 3, 0 };
@ -192,10 +178,9 @@ static void _ldiv5(uint32_t value[])
*v = quot;
}
static char _get_digit(uint32_t fract[], int *digit_count)
static char _get_digit(uint64_t *fr, int *digit_count)
{
int rval;
uint64_t *fr = (uint64_t *)&fract[0];
if (*digit_count > 0) {
*digit_count -= 1;
@ -230,37 +215,31 @@ static char _get_digit(uint32_t fract[], int *digit_count)
*/
#define MAXFP1 0xFFFFFFFF /* Largest # if first fp format */
#define MAXFP2 0x0FFFFFFF /* Largest # in second fp format */
#define HIGHBIT64 (1ull<<63)
static int _to_float(char *buf, uint32_t double_temp[], int c,
static int _to_float(char *buf, uint64_t double_temp, int c,
int falt, int fplus, int fspace, int precision)
{
register int decexp;
register int exp;
int sign;
int digit_count;
uint32_t fract[2];
uint32_t ltemp[2];
uint64_t fract;
uint64_t ltemp;
int prune_zero;
char *start = buf;
exp = (double_temp[1] >> 20) & 0x7FF;
fract[1] = (double_temp[1] << 11) & 0x7FFFF800;
fract[1] |= ((double_temp[0] >> 21) & 0x000007FF);
fract[0] = double_temp[0] << 11;
exp = double_temp >> 52 & 0x7ff;
fract = (double_temp << 11) & ~HIGHBIT64;
sign = !!(double_temp & HIGHBIT64);
if (exp == 0x7FF) {
if ((fract[1] | fract[0]) == 0) {
if ((double_temp[1] & 0x80000000)) {
*buf++ = '-';
*buf++ = 'I';
*buf++ = 'N';
*buf++ = 'F';
} else {
*buf++ = '+';
*buf++ = 'I';
*buf++ = 'N';
*buf++ = 'F';
}
if (exp == 0x7ff) {
if (!fract) {
*buf++ = sign ? '-' : '+';
*buf++ = 'I';
*buf++ = 'N';
*buf++ = 'F';
} else {
*buf++ = 'N';
*buf++ = 'a';
@ -270,52 +249,49 @@ static int _to_float(char *buf, uint32_t double_temp[], int c,
return buf - start;
}
if ((exp | fract[1] | fract[0]) != 0) {
if ((exp | fract) != 0) {
exp -= (1023 - 1); /* +1 since .1 vs 1. */
fract[1] |= 0x80000000;
fract |= HIGHBIT64;
decexp = true; /* Wasn't zero */
} else
decexp = false; /* It was zero */
if (decexp && (double_temp[1] & 0x80000000)) {
if (decexp && sign) {
*buf++ = '-';
} else if (fplus)
} else if (fplus) {
*buf++ = '+';
else if (fspace)
} else if (fspace) {
*buf++ = ' ';
}
decexp = 0;
while (exp <= -3) {
while (fract[1] >= (MAXFP1 / 5)) {
_rlrshift(fract);
while ((fract >> 32) >= (MAXFP1 / 5)) {
_rlrshift(&fract);
exp++;
}
ltemp[0] = fract[0];
ltemp[1] = fract[1];
_llshift(fract);
_llshift(fract);
_ladd(fract, ltemp);
fract *= 5;
exp++;
decexp--;
while (fract[1] <= (MAXFP1 / 2)) {
_llshift(fract);
while ((fract >> 32) <= (MAXFP1 / 2)) {
fract <<= 1;
exp--;
}
}
while (exp > 0) {
_ldiv5(fract);
_ldiv5(&fract);
exp--;
decexp++;
while (fract[1] <= (MAXFP1 / 2)) {
_llshift(fract);
while ((fract >> 32) <= (MAXFP1 / 2)) {
fract <<= 1;
exp--;
}
}
while (exp < (0 + 4)) {
_rlrshift(fract);
_rlrshift(&fract);
exp++;
}
@ -344,24 +320,23 @@ static int _to_float(char *buf, uint32_t double_temp[], int c,
if (exp > 16)
exp = 16;
ltemp[0] = 0;
ltemp[1] = 0x08000000;
ltemp = 0x0800000000000000;
while (exp--) {
_ldiv5(ltemp);
_rlrshift(ltemp);
_ldiv5(&ltemp);
_rlrshift(&ltemp);
}
_ladd(fract, ltemp);
if (fract[1] & 0xF0000000) {
_ldiv5(fract);
_rlrshift(fract);
fract += ltemp;
if ((fract >> 32) & 0xF0000000) {
_ldiv5(&fract);
_rlrshift(&fract);
decexp++;
}
if (c == 'f') {
if (decexp > 0) {
while (decexp > 0) {
*buf++ = _get_digit(fract, &digit_count);
*buf++ = _get_digit(&fract, &digit_count);
decexp--;
}
} else
@ -373,16 +348,16 @@ static int _to_float(char *buf, uint32_t double_temp[], int c,
*buf++ = '0';
decexp++;
} else
*buf++ = _get_digit(fract, &digit_count);
*buf++ = _get_digit(&fract, &digit_count);
}
} else {
*buf = _get_digit(fract, &digit_count);
*buf = _get_digit(&fract, &digit_count);
if (*buf++ != '0')
decexp--;
if (falt || (precision > 0))
*buf++ = '.';
while (precision-- > 0)
*buf++ = _get_digit(fract, &digit_count);
*buf++ = _get_digit(&fract, &digit_count);
}
if (prune_zero) {
@ -450,7 +425,7 @@ int _prf(int (*func)(), void *dest, char *format, va_list vargs)
int32_t *int32ptr_temp;
int32_t int32_temp;
uint32_t uint32_temp;
uint32_t double_temp[2];
uint64_t double_temp;
count = 0;
@ -599,20 +574,11 @@ int _prf(int (*func)(), void *dest, char *format, va_list vargs)
{
union {
double d;
struct {
uint32_t u1;
uint32_t u2;
} s;
uint64_t i;
} u;
u.d = (double) va_arg(vargs, double);
#if defined(_BIG_ENDIAN)
double_temp[0] = u.s.u2;
double_temp[1] = u.s.u1;
#else
double_temp[0] = u.s.u1;
double_temp[1] = u.s.u2;
#endif
double_temp = u.i;
}
c = _to_float(buf, double_temp, c, falt, fplus,