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linux/arch/arm/vfp/vfpdouble.c
Russell King 928bd1b470 [ARM] vfp: fix leak of VFP_NAN_FLAG into FPSCR 
The VFP code can leak VFP_NAN_FLAG into the FPSCR. It doesn't correspond
to any real FPSCR bit (and overlaps one of the exception flags).

Bug report from Daniel Jacobowitz

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-04-25 20:41:27 +01:00

1193 lines
28 KiB
C
Raw Blame History

/*
* linux/arch/arm/vfp/vfpdouble.c
*
* This code is derived in part from John R. Housers softfloat library, which
* carries the following notice:
*
* ===========================================================================
* This C source file is part of the SoftFloat IEC/IEEE Floating-point
* Arithmetic Package, Release 2.
*
* Written by John R. Hauser. This work was made possible in part by the
* International Computer Science Institute, located at Suite 600, 1947 Center
* Street, Berkeley, California 94704. Funding was partially provided by the
* National Science Foundation under grant MIP-9311980. The original version
* of this code was written as part of a project to build a fixed-point vector
* processor in collaboration with the University of California at Berkeley,
* overseen by Profs. Nelson Morgan and John Wawrzynek. More information
* is available through the web page `http://HTTP.CS.Berkeley.EDU/~jhauser/
* arithmetic/softfloat.html'.
*
* THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE. Although reasonable effort
* has been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT
* TIMES RESULT IN INCORRECT BEHAVIOR. USE OF THIS SOFTWARE IS RESTRICTED TO
* PERSONS AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL RESPONSIBILITY FOR ANY
* AND ALL LOSSES, COSTS, OR OTHER PROBLEMS ARISING FROM ITS USE.
*
* Derivative works are acceptable, even for commercial purposes, so long as
* (1) they include prominent notice that the work is derivative, and (2) they
* include prominent notice akin to these three paragraphs for those parts of
* this code that are retained.
* ===========================================================================
*/
#include <linux/kernel.h>
#include <linux/bitops.h>
#include <asm/div64.h>
#include <asm/ptrace.h>
#include <asm/vfp.h>
#include "vfpinstr.h"
#include "vfp.h"
static struct vfp_double vfp_double_default_qnan = {
.exponent = 2047,
.sign = 0,
.significand = VFP_DOUBLE_SIGNIFICAND_QNAN,
};
static void vfp_double_dump(const char *str, struct vfp_double *d)
{
pr_debug("VFP: %s: sign=%d exponent=%d significand=%016llx\n",
str, d->sign != 0, d->exponent, d->significand);
}
static void vfp_double_normalise_denormal(struct vfp_double *vd)
{
int bits = 31 - fls(vd->significand >> 32);
if (bits == 31)
bits = 62 - fls(vd->significand);
vfp_double_dump("normalise_denormal: in", vd);
if (bits) {
vd->exponent -= bits - 1;
vd->significand <<= bits;
}
vfp_double_dump("normalise_denormal: out", vd);
}
u32 vfp_double_normaliseround(int dd, struct vfp_double *vd, u32 fpscr, u32 exceptions, const char *func)
{
u64 significand, incr;
int exponent, shift, underflow;
u32 rmode;
vfp_double_dump("pack: in", vd);
/*
* Infinities and NaNs are a special case.
*/
if (vd->exponent == 2047 && (vd->significand == 0 || exceptions))
goto pack;
/*
* Special-case zero.
*/
if (vd->significand == 0) {
vd->exponent = 0;
goto pack;
}
exponent = vd->exponent;
significand = vd->significand;
shift = 32 - fls(significand >> 32);
if (shift == 32)
shift = 64 - fls(significand);
if (shift) {
exponent -= shift;
significand <<= shift;
}
#ifdef DEBUG
vd->exponent = exponent;
vd->significand = significand;
vfp_double_dump("pack: normalised", vd);
#endif
/*
* Tiny number?
*/
underflow = exponent < 0;
if (underflow) {
significand = vfp_shiftright64jamming(significand, -exponent);
exponent = 0;
#ifdef DEBUG
vd->exponent = exponent;
vd->significand = significand;
vfp_double_dump("pack: tiny number", vd);
#endif
if (!(significand & ((1ULL << (VFP_DOUBLE_LOW_BITS + 1)) - 1)))
underflow = 0;
}
/*
* Select rounding increment.
*/
incr = 0;
rmode = fpscr & FPSCR_RMODE_MASK;
if (rmode == FPSCR_ROUND_NEAREST) {
incr = 1ULL << VFP_DOUBLE_LOW_BITS;
if ((significand & (1ULL << (VFP_DOUBLE_LOW_BITS + 1))) == 0)
incr -= 1;
} else if (rmode == FPSCR_ROUND_TOZERO) {
incr = 0;
} else if ((rmode == FPSCR_ROUND_PLUSINF) ^ (vd->sign != 0))
incr = (1ULL << (VFP_DOUBLE_LOW_BITS + 1)) - 1;
pr_debug("VFP: rounding increment = 0x%08llx\n", incr);
/*
* Is our rounding going to overflow?
*/
if ((significand + incr) < significand) {
exponent += 1;
significand = (significand >> 1) | (significand & 1);
incr >>= 1;
#ifdef DEBUG
vd->exponent = exponent;
vd->significand = significand;
vfp_double_dump("pack: overflow", vd);
#endif
}
/*
* If any of the low bits (which will be shifted out of the
* number) are non-zero, the result is inexact.
*/
if (significand & ((1 << (VFP_DOUBLE_LOW_BITS + 1)) - 1))
exceptions |= FPSCR_IXC;
/*
* Do our rounding.
*/
significand += incr;
/*
* Infinity?
*/
if (exponent >= 2046) {
exceptions |= FPSCR_OFC | FPSCR_IXC;
if (incr == 0) {
vd->exponent = 2045;
vd->significand = 0x7fffffffffffffffULL;
} else {
vd->exponent = 2047; /* infinity */
vd->significand = 0;
}
} else {
if (significand >> (VFP_DOUBLE_LOW_BITS + 1) == 0)
exponent = 0;
if (exponent || significand > 0x8000000000000000ULL)
underflow = 0;
if (underflow)
exceptions |= FPSCR_UFC;
vd->exponent = exponent;
vd->significand = significand >> 1;
}
pack:
vfp_double_dump("pack: final", vd);
{
s64 d = vfp_double_pack(vd);
pr_debug("VFP: %s: d(d%d)=%016llx exceptions=%08x\n", func,
dd, d, exceptions);
vfp_put_double(dd, d);
}
return exceptions;
}
/*
* Propagate the NaN, setting exceptions if it is signalling.
* 'n' is always a NaN. 'm' may be a number, NaN or infinity.
*/
static u32
vfp_propagate_nan(struct vfp_double *vdd, struct vfp_double *vdn,
struct vfp_double *vdm, u32 fpscr)
{
struct vfp_double *nan;
int tn, tm = 0;
tn = vfp_double_type(vdn);
if (vdm)
tm = vfp_double_type(vdm);
if (fpscr & FPSCR_DEFAULT_NAN)
/*
* Default NaN mode - always returns a quiet NaN
*/
nan = &vfp_double_default_qnan;
else {
/*
* Contemporary mode - select the first signalling
* NAN, or if neither are signalling, the first
* quiet NAN.
*/
if (tn == VFP_SNAN || (tm != VFP_SNAN && tn == VFP_QNAN))
nan = vdn;
else
nan = vdm;
/*
* Make the NaN quiet.
*/
nan->significand |= VFP_DOUBLE_SIGNIFICAND_QNAN;
}
*vdd = *nan;
/*
* If one was a signalling NAN, raise invalid operation.
*/
return tn == VFP_SNAN || tm == VFP_SNAN ? FPSCR_IOC : VFP_NAN_FLAG;
}
/*
* Extended operations
*/
static u32 vfp_double_fabs(int dd, int unused, int dm, u32 fpscr)
{
vfp_put_double(dd, vfp_double_packed_abs(vfp_get_double(dm)));
return 0;
}
static u32 vfp_double_fcpy(int dd, int unused, int dm, u32 fpscr)
{
vfp_put_double(dd, vfp_get_double(dm));
return 0;
}
static u32 vfp_double_fneg(int dd, int unused, int dm, u32 fpscr)
{
vfp_put_double(dd, vfp_double_packed_negate(vfp_get_double(dm)));
return 0;
}
static u32 vfp_double_fsqrt(int dd, int unused, int dm, u32 fpscr)
{
struct vfp_double vdm, vdd;
int ret, tm;
vfp_double_unpack(&vdm, vfp_get_double(dm));
tm = vfp_double_type(&vdm);
if (tm & (VFP_NAN|VFP_INFINITY)) {
struct vfp_double *vdp = &vdd;
if (tm & VFP_NAN)
ret = vfp_propagate_nan(vdp, &vdm, NULL, fpscr);
else if (vdm.sign == 0) {
sqrt_copy:
vdp = &vdm;
ret = 0;
} else {
sqrt_invalid:
vdp = &vfp_double_default_qnan;
ret = FPSCR_IOC;
}
vfp_put_double(dd, vfp_double_pack(vdp));
return ret;
}
/*
* sqrt(+/- 0) == +/- 0
*/
if (tm & VFP_ZERO)
goto sqrt_copy;
/*
* Normalise a denormalised number
*/
if (tm & VFP_DENORMAL)
vfp_double_normalise_denormal(&vdm);
/*
* sqrt(<0) = invalid
*/
if (vdm.sign)
goto sqrt_invalid;
vfp_double_dump("sqrt", &vdm);
/*
* Estimate the square root.
*/
vdd.sign = 0;
vdd.exponent = ((vdm.exponent - 1023) >> 1) + 1023;
vdd.significand = (u64)vfp_estimate_sqrt_significand(vdm.exponent, vdm.significand >> 32) << 31;
vfp_double_dump("sqrt estimate1", &vdd);
vdm.significand >>= 1 + (vdm.exponent & 1);
vdd.significand += 2 + vfp_estimate_div128to64(vdm.significand, 0, vdd.significand);
vfp_double_dump("sqrt estimate2", &vdd);
/*
* And now adjust.
*/
if ((vdd.significand & VFP_DOUBLE_LOW_BITS_MASK) <= 5) {
if (vdd.significand < 2) {
vdd.significand = ~0ULL;
} else {
u64 termh, terml, remh, reml;
vdm.significand <<= 2;
mul64to128(&termh, &terml, vdd.significand, vdd.significand);
sub128(&remh, &reml, vdm.significand, 0, termh, terml);
while ((s64)remh < 0) {
vdd.significand -= 1;
shift64left(&termh, &terml, vdd.significand);
terml |= 1;
add128(&remh, &reml, remh, reml, termh, terml);
}
vdd.significand |= (remh | reml) != 0;
}
}
vdd.significand = vfp_shiftright64jamming(vdd.significand, 1);
return vfp_double_normaliseround(dd, &vdd, fpscr, 0, "fsqrt");
}
/*
* Equal := ZC
* Less than := N
* Greater than := C
* Unordered := CV
*/
static u32 vfp_compare(int dd, int signal_on_qnan, int dm, u32 fpscr)
{
s64 d, m;
u32 ret = 0;
m = vfp_get_double(dm);
if (vfp_double_packed_exponent(m) == 2047 && vfp_double_packed_mantissa(m)) {
ret |= FPSCR_C | FPSCR_V;
if (signal_on_qnan || !(vfp_double_packed_mantissa(m) & (1ULL << (VFP_DOUBLE_MANTISSA_BITS - 1))))
/*
* Signalling NaN, or signalling on quiet NaN
*/
ret |= FPSCR_IOC;
}
d = vfp_get_double(dd);
if (vfp_double_packed_exponent(d) == 2047 && vfp_double_packed_mantissa(d)) {
ret |= FPSCR_C | FPSCR_V;
if (signal_on_qnan || !(vfp_double_packed_mantissa(d) & (1ULL << (VFP_DOUBLE_MANTISSA_BITS - 1))))
/*
* Signalling NaN, or signalling on quiet NaN
*/
ret |= FPSCR_IOC;
}
if (ret == 0) {
if (d == m || vfp_double_packed_abs(d | m) == 0) {
/*
* equal
*/
ret |= FPSCR_Z | FPSCR_C;
} else if (vfp_double_packed_sign(d ^ m)) {
/*
* different signs
*/
if (vfp_double_packed_sign(d))
/*
* d is negative, so d < m
*/
ret |= FPSCR_N;
else
/*
* d is positive, so d > m
*/
ret |= FPSCR_C;
} else if ((vfp_double_packed_sign(d) != 0) ^ (d < m)) {
/*
* d < m
*/
ret |= FPSCR_N;
} else if ((vfp_double_packed_sign(d) != 0) ^ (d > m)) {
/*
* d > m
*/
ret |= FPSCR_C;
}
}
return ret;
}
static u32 vfp_double_fcmp(int dd, int unused, int dm, u32 fpscr)
{
return vfp_compare(dd, 0, dm, fpscr);
}
static u32 vfp_double_fcmpe(int dd, int unused, int dm, u32 fpscr)
{
return vfp_compare(dd, 1, dm, fpscr);
}
static u32 vfp_double_fcmpz(int dd, int unused, int dm, u32 fpscr)
{
return vfp_compare(dd, 0, VFP_REG_ZERO, fpscr);
}
static u32 vfp_double_fcmpez(int dd, int unused, int dm, u32 fpscr)
{
return vfp_compare(dd, 1, VFP_REG_ZERO, fpscr);
}
static u32 vfp_double_fcvts(int sd, int unused, int dm, u32 fpscr)
{
struct vfp_double vdm;
struct vfp_single vsd;
int tm;
u32 exceptions = 0;
vfp_double_unpack(&vdm, vfp_get_double(dm));
tm = vfp_double_type(&vdm);
/*
* If we have a signalling NaN, signal invalid operation.
*/
if (tm == VFP_SNAN)
exceptions = FPSCR_IOC;
if (tm & VFP_DENORMAL)
vfp_double_normalise_denormal(&vdm);
vsd.sign = vdm.sign;
vsd.significand = vfp_hi64to32jamming(vdm.significand);
/*
* If we have an infinity or a NaN, the exponent must be 255
*/
if (tm & (VFP_INFINITY|VFP_NAN)) {
vsd.exponent = 255;
if (tm & VFP_NAN)
vsd.significand |= VFP_SINGLE_SIGNIFICAND_QNAN;
goto pack_nan;
} else if (tm & VFP_ZERO)
vsd.exponent = 0;
else
vsd.exponent = vdm.exponent - (1023 - 127);
return vfp_single_normaliseround(sd, &vsd, fpscr, exceptions, "fcvts");
pack_nan:
vfp_put_float(sd, vfp_single_pack(&vsd));
return exceptions;
}
static u32 vfp_double_fuito(int dd, int unused, int dm, u32 fpscr)
{
struct vfp_double vdm;
u32 m = vfp_get_float(dm);
vdm.sign = 0;
vdm.exponent = 1023 + 63 - 1;
vdm.significand = (u64)m;
return vfp_double_normaliseround(dd, &vdm, fpscr, 0, "fuito");
}
static u32 vfp_double_fsito(int dd, int unused, int dm, u32 fpscr)
{
struct vfp_double vdm;
u32 m = vfp_get_float(dm);
vdm.sign = (m & 0x80000000) >> 16;
vdm.exponent = 1023 + 63 - 1;
vdm.significand = vdm.sign ? -m : m;
return vfp_double_normaliseround(dd, &vdm, fpscr, 0, "fsito");
}
static u32 vfp_double_ftoui(int sd, int unused, int dm, u32 fpscr)
{
struct vfp_double vdm;
u32 d, exceptions = 0;
int rmode = fpscr & FPSCR_RMODE_MASK;
int tm;
vfp_double_unpack(&vdm, vfp_get_double(dm));
/*
* Do we have a denormalised number?
*/
tm = vfp_double_type(&vdm);
if (tm & VFP_DENORMAL)
exceptions |= FPSCR_IDC;
if (tm & VFP_NAN)
vdm.sign = 0;
if (vdm.exponent >= 1023 + 32) {
d = vdm.sign ? 0 : 0xffffffff;
exceptions = FPSCR_IOC;
} else if (vdm.exponent >= 1023 - 1) {
int shift = 1023 + 63 - vdm.exponent;
u64 rem, incr = 0;
/*
* 2^0 <= m < 2^32-2^8
*/
d = (vdm.significand << 1) >> shift;
rem = vdm.significand << (65 - shift);
if (rmode == FPSCR_ROUND_NEAREST) {
incr = 0x8000000000000000ULL;
if ((d & 1) == 0)
incr -= 1;
} else if (rmode == FPSCR_ROUND_TOZERO) {
incr = 0;
} else if ((rmode == FPSCR_ROUND_PLUSINF) ^ (vdm.sign != 0)) {
incr = ~0ULL;
}
if ((rem + incr) < rem) {
if (d < 0xffffffff)
d += 1;
else
exceptions |= FPSCR_IOC;
}
if (d && vdm.sign) {
d = 0;
exceptions |= FPSCR_IOC;
} else if (rem)
exceptions |= FPSCR_IXC;
} else {
d = 0;
if (vdm.exponent | vdm.significand) {
exceptions |= FPSCR_IXC;
if (rmode == FPSCR_ROUND_PLUSINF && vdm.sign == 0)
d = 1;
else if (rmode == FPSCR_ROUND_MINUSINF && vdm.sign) {
d = 0;
exceptions |= FPSCR_IOC;
}
}
}
pr_debug("VFP: ftoui: d(s%d)=%08x exceptions=%08x\n", sd, d, exceptions);
vfp_put_float(sd, d);
return exceptions;
}
static u32 vfp_double_ftouiz(int sd, int unused, int dm, u32 fpscr)
{
return vfp_double_ftoui(sd, unused, dm, FPSCR_ROUND_TOZERO);
}
static u32 vfp_double_ftosi(int sd, int unused, int dm, u32 fpscr)
{
struct vfp_double vdm;
u32 d, exceptions = 0;
int rmode = fpscr & FPSCR_RMODE_MASK;
int tm;
vfp_double_unpack(&vdm, vfp_get_double(dm));
vfp_double_dump("VDM", &vdm);
/*
* Do we have denormalised number?
*/
tm = vfp_double_type(&vdm);
if (tm & VFP_DENORMAL)
exceptions |= FPSCR_IDC;
if (tm & VFP_NAN) {
d = 0;
exceptions |= FPSCR_IOC;
} else if (vdm.exponent >= 1023 + 32) {
d = 0x7fffffff;
if (vdm.sign)
d = ~d;
exceptions |= FPSCR_IOC;
} else if (vdm.exponent >= 1023 - 1) {
int shift = 1023 + 63 - vdm.exponent; /* 58 */
u64 rem, incr = 0;
d = (vdm.significand << 1) >> shift;
rem = vdm.significand << (65 - shift);
if (rmode == FPSCR_ROUND_NEAREST) {
incr = 0x8000000000000000ULL;
if ((d & 1) == 0)
incr -= 1;
} else if (rmode == FPSCR_ROUND_TOZERO) {
incr = 0;
} else if ((rmode == FPSCR_ROUND_PLUSINF) ^ (vdm.sign != 0)) {
incr = ~0ULL;
}
if ((rem + incr) < rem && d < 0xffffffff)
d += 1;
if (d > 0x7fffffff + (vdm.sign != 0)) {
d = 0x7fffffff + (vdm.sign != 0);
exceptions |= FPSCR_IOC;
} else if (rem)
exceptions |= FPSCR_IXC;
if (vdm.sign)
d = -d;
} else {
d = 0;
if (vdm.exponent | vdm.significand) {
exceptions |= FPSCR_IXC;
if (rmode == FPSCR_ROUND_PLUSINF && vdm.sign == 0)
d = 1;
else if (rmode == FPSCR_ROUND_MINUSINF && vdm.sign)
d = -1;
}
}
pr_debug("VFP: ftosi: d(s%d)=%08x exceptions=%08x\n", sd, d, exceptions);
vfp_put_float(sd, (s32)d);
return exceptions;
}
static u32 vfp_double_ftosiz(int dd, int unused, int dm, u32 fpscr)
{
return vfp_double_ftosi(dd, unused, dm, FPSCR_ROUND_TOZERO);
}
static u32 (* const fop_extfns[32])(int dd, int unused, int dm, u32 fpscr) = {
[FEXT_TO_IDX(FEXT_FCPY)] = vfp_double_fcpy,
[FEXT_TO_IDX(FEXT_FABS)] = vfp_double_fabs,
[FEXT_TO_IDX(FEXT_FNEG)] = vfp_double_fneg,
[FEXT_TO_IDX(FEXT_FSQRT)] = vfp_double_fsqrt,
[FEXT_TO_IDX(FEXT_FCMP)] = vfp_double_fcmp,
[FEXT_TO_IDX(FEXT_FCMPE)] = vfp_double_fcmpe,
[FEXT_TO_IDX(FEXT_FCMPZ)] = vfp_double_fcmpz,
[FEXT_TO_IDX(FEXT_FCMPEZ)] = vfp_double_fcmpez,
[FEXT_TO_IDX(FEXT_FCVT)] = vfp_double_fcvts,
[FEXT_TO_IDX(FEXT_FUITO)] = vfp_double_fuito,
[FEXT_TO_IDX(FEXT_FSITO)] = vfp_double_fsito,
[FEXT_TO_IDX(FEXT_FTOUI)] = vfp_double_ftoui,
[FEXT_TO_IDX(FEXT_FTOUIZ)] = vfp_double_ftouiz,
[FEXT_TO_IDX(FEXT_FTOSI)] = vfp_double_ftosi,
[FEXT_TO_IDX(FEXT_FTOSIZ)] = vfp_double_ftosiz,
};
static u32
vfp_double_fadd_nonnumber(struct vfp_double *vdd, struct vfp_double *vdn,
struct vfp_double *vdm, u32 fpscr)
{
struct vfp_double *vdp;
u32 exceptions = 0;
int tn, tm;
tn = vfp_double_type(vdn);
tm = vfp_double_type(vdm);
if (tn & tm & VFP_INFINITY) {
/*
* Two infinities. Are they different signs?
*/
if (vdn->sign ^ vdm->sign) {
/*
* different signs -> invalid
*/
exceptions = FPSCR_IOC;
vdp = &vfp_double_default_qnan;
} else {
/*
* same signs -> valid
*/
vdp = vdn;
}
} else if (tn & VFP_INFINITY && tm & VFP_NUMBER) {
/*
* One infinity and one number -> infinity
*/
vdp = vdn;
} else {
/*
* 'n' is a NaN of some type
*/
return vfp_propagate_nan(vdd, vdn, vdm, fpscr);
}
*vdd = *vdp;
return exceptions;
}
static u32
vfp_double_add(struct vfp_double *vdd, struct vfp_double *vdn,
struct vfp_double *vdm, u32 fpscr)
{
u32 exp_diff;
u64 m_sig;
if (vdn->significand & (1ULL << 63) ||
vdm->significand & (1ULL << 63)) {
pr_info("VFP: bad FP values in %s\n", __func__);
vfp_double_dump("VDN", vdn);
vfp_double_dump("VDM", vdm);
}
/*
* Ensure that 'n' is the largest magnitude number. Note that
* if 'n' and 'm' have equal exponents, we do not swap them.
* This ensures that NaN propagation works correctly.
*/
if (vdn->exponent < vdm->exponent) {
struct vfp_double *t = vdn;
vdn = vdm;
vdm = t;
}
/*
* Is 'n' an infinity or a NaN? Note that 'm' may be a number,
* infinity or a NaN here.
*/
if (vdn->exponent == 2047)
return vfp_double_fadd_nonnumber(vdd, vdn, vdm, fpscr);
/*
* We have two proper numbers, where 'vdn' is the larger magnitude.
*
* Copy 'n' to 'd' before doing the arithmetic.
*/
*vdd = *vdn;
/*
* Align 'm' with the result.
*/
exp_diff = vdn->exponent - vdm->exponent;
m_sig = vfp_shiftright64jamming(vdm->significand, exp_diff);
/*
* If the signs are different, we are really subtracting.
*/
if (vdn->sign ^ vdm->sign) {
m_sig = vdn->significand - m_sig;
if ((s64)m_sig < 0) {
vdd->sign = vfp_sign_negate(vdd->sign);
m_sig = -m_sig;
} else if (m_sig == 0) {
vdd->sign = (fpscr & FPSCR_RMODE_MASK) ==
FPSCR_ROUND_MINUSINF ? 0x8000 : 0;
}
} else {
m_sig += vdn->significand;
}
vdd->significand = m_sig;
return 0;
}
static u32
vfp_double_multiply(struct vfp_double *vdd, struct vfp_double *vdn,
struct vfp_double *vdm, u32 fpscr)
{
vfp_double_dump("VDN", vdn);
vfp_double_dump("VDM", vdm);
/*
* Ensure that 'n' is the largest magnitude number. Note that
* if 'n' and 'm' have equal exponents, we do not swap them.
* This ensures that NaN propagation works correctly.
*/
if (vdn->exponent < vdm->exponent) {
struct vfp_double *t = vdn;
vdn = vdm;
vdm = t;
pr_debug("VFP: swapping M <-> N\n");
}
vdd->sign = vdn->sign ^ vdm->sign;
/*
* If 'n' is an infinity or NaN, handle it. 'm' may be anything.
*/
if (vdn->exponent == 2047) {
if (vdn->significand || (vdm->exponent == 2047 && vdm->significand))
return vfp_propagate_nan(vdd, vdn, vdm, fpscr);
if ((vdm->exponent | vdm->significand) == 0) {
*vdd = vfp_double_default_qnan;
return FPSCR_IOC;
}
vdd->exponent = vdn->exponent;
vdd->significand = 0;
return 0;
}
/*
* If 'm' is zero, the result is always zero. In this case,
* 'n' may be zero or a number, but it doesn't matter which.
*/
if ((vdm->exponent | vdm->significand) == 0) {
vdd->exponent = 0;
vdd->significand = 0;
return 0;
}
/*
* We add 2 to the destination exponent for the same reason
* as the addition case - though this time we have +1 from
* each input operand.
*/
vdd->exponent = vdn->exponent + vdm->exponent - 1023 + 2;
vdd->significand = vfp_hi64multiply64(vdn->significand, vdm->significand);
vfp_double_dump("VDD", vdd);
return 0;
}
#define NEG_MULTIPLY (1 << 0)
#define NEG_SUBTRACT (1 << 1)
static u32
vfp_double_multiply_accumulate(int dd, int dn, int dm, u32 fpscr, u32 negate, char *func)
{
struct vfp_double vdd, vdp, vdn, vdm;
u32 exceptions;
vfp_double_unpack(&vdn, vfp_get_double(dn));
if (vdn.exponent == 0 && vdn.significand)
vfp_double_normalise_denormal(&vdn);
vfp_double_unpack(&vdm, vfp_get_double(dm));
if (vdm.exponent == 0 && vdm.significand)
vfp_double_normalise_denormal(&vdm);
exceptions = vfp_double_multiply(&vdp, &vdn, &vdm, fpscr);
if (negate & NEG_MULTIPLY)
vdp.sign = vfp_sign_negate(vdp.sign);
vfp_double_unpack(&vdn, vfp_get_double(dd));
if (negate & NEG_SUBTRACT)
vdn.sign = vfp_sign_negate(vdn.sign);
exceptions |= vfp_double_add(&vdd, &vdn, &vdp, fpscr);
return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, func);
}
/*
* Standard operations
*/
/*
* sd = sd + (sn * sm)
*/
static u32 vfp_double_fmac(int dd, int dn, int dm, u32 fpscr)
{
return vfp_double_multiply_accumulate(dd, dn, dm, fpscr, 0, "fmac");
}
/*
* sd = sd - (sn * sm)
*/
static u32 vfp_double_fnmac(int dd, int dn, int dm, u32 fpscr)
{
return vfp_double_multiply_accumulate(dd, dn, dm, fpscr, NEG_MULTIPLY, "fnmac");
}
/*
* sd = -sd + (sn * sm)
*/
static u32 vfp_double_fmsc(int dd, int dn, int dm, u32 fpscr)
{
return vfp_double_multiply_accumulate(dd, dn, dm, fpscr, NEG_SUBTRACT, "fmsc");
}
/*
* sd = -sd - (sn * sm)
*/
static u32 vfp_double_fnmsc(int dd, int dn, int dm, u32 fpscr)
{
return vfp_double_multiply_accumulate(dd, dn, dm, fpscr, NEG_SUBTRACT | NEG_MULTIPLY, "fnmsc");
}
/*
* sd = sn * sm
*/
static u32 vfp_double_fmul(int dd, int dn, int dm, u32 fpscr)
{
struct vfp_double vdd, vdn, vdm;
u32 exceptions;
vfp_double_unpack(&vdn, vfp_get_double(dn));
if (vdn.exponent == 0 && vdn.significand)
vfp_double_normalise_denormal(&vdn);
vfp_double_unpack(&vdm, vfp_get_double(dm));
if (vdm.exponent == 0 && vdm.significand)
vfp_double_normalise_denormal(&vdm);
exceptions = vfp_double_multiply(&vdd, &vdn, &vdm, fpscr);
return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fmul");
}
/*
* sd = -(sn * sm)
*/
static u32 vfp_double_fnmul(int dd, int dn, int dm, u32 fpscr)
{
struct vfp_double vdd, vdn, vdm;
u32 exceptions;
vfp_double_unpack(&vdn, vfp_get_double(dn));
if (vdn.exponent == 0 && vdn.significand)
vfp_double_normalise_denormal(&vdn);
vfp_double_unpack(&vdm, vfp_get_double(dm));
if (vdm.exponent == 0 && vdm.significand)
vfp_double_normalise_denormal(&vdm);
exceptions = vfp_double_multiply(&vdd, &vdn, &vdm, fpscr);
vdd.sign = vfp_sign_negate(vdd.sign);
return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fnmul");
}
/*
* sd = sn + sm
*/
static u32 vfp_double_fadd(int dd, int dn, int dm, u32 fpscr)
{
struct vfp_double vdd, vdn, vdm;
u32 exceptions;
vfp_double_unpack(&vdn, vfp_get_double(dn));
if (vdn.exponent == 0 && vdn.significand)
vfp_double_normalise_denormal(&vdn);
vfp_double_unpack(&vdm, vfp_get_double(dm));
if (vdm.exponent == 0 && vdm.significand)
vfp_double_normalise_denormal(&vdm);
exceptions = vfp_double_add(&vdd, &vdn, &vdm, fpscr);
return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fadd");
}
/*
* sd = sn - sm
*/
static u32 vfp_double_fsub(int dd, int dn, int dm, u32 fpscr)
{
struct vfp_double vdd, vdn, vdm;
u32 exceptions;
vfp_double_unpack(&vdn, vfp_get_double(dn));
if (vdn.exponent == 0 && vdn.significand)
vfp_double_normalise_denormal(&vdn);
vfp_double_unpack(&vdm, vfp_get_double(dm));
if (vdm.exponent == 0 && vdm.significand)
vfp_double_normalise_denormal(&vdm);
/*
* Subtraction is like addition, but with a negated operand.
*/
vdm.sign = vfp_sign_negate(vdm.sign);
exceptions = vfp_double_add(&vdd, &vdn, &vdm, fpscr);
return vfp_double_normaliseround(dd, &vdd, fpscr, exceptions, "fsub");
}
/*
* sd = sn / sm
*/
static u32 vfp_double_fdiv(int dd, int dn, int dm, u32 fpscr)
{
struct vfp_double vdd, vdn, vdm;
u32 exceptions = 0;
int tm, tn;
vfp_double_unpack(&vdn, vfp_get_double(dn));
vfp_double_unpack(&vdm, vfp_get_double(dm));
vdd.sign = vdn.sign ^ vdm.sign;
tn = vfp_double_type(&vdn);
tm = vfp_double_type(&vdm);
/*
* Is n a NAN?
*/
if (tn & VFP_NAN)
goto vdn_nan;
/*
* Is m a NAN?
*/
if (tm & VFP_NAN)
goto vdm_nan;
/*
* If n and m are infinity, the result is invalid
* If n and m are zero, the result is invalid
*/
if (tm & tn & (VFP_INFINITY|VFP_ZERO))
goto invalid;
/*
* If n is infinity, the result is infinity
*/
if (tn & VFP_INFINITY)
goto infinity;
/*
* If m is zero, raise div0 exceptions
*/
if (tm & VFP_ZERO)
goto divzero;
/*
* If m is infinity, or n is zero, the result is zero
*/
if (tm & VFP_INFINITY || tn & VFP_ZERO)
goto zero;
if (tn & VFP_DENORMAL)
vfp_double_normalise_denormal(&vdn);
if (tm & VFP_DENORMAL)
vfp_double_normalise_denormal(&vdm);
/*
* Ok, we have two numbers, we can perform division.
*/
vdd.exponent = vdn.exponent - vdm.exponent + 1023 - 1;
vdm.significand <<= 1;
if (vdm.significand <= (2 * vdn.significand)) {
vdn.significand >>= 1;
vdd.exponent++;
}
vdd.significand = vfp_estimate_div128to64(vdn.significand, 0, vdm.significand);
if ((vdd.significand & 0x1ff) <= 2) {
u64 termh, terml, remh, reml;
mul64to128(&termh, &terml, vdm.significand, vdd.significand);
sub128(&remh, &reml, vdn.significand, 0, termh, terml);
while ((s64)remh < 0) {
vdd.significand -= 1;
add128(&remh, &reml, remh, reml, 0, vdm.significand);
}
vdd.significand |= (reml != 0);
}
return vfp_double_normaliseround(dd, &vdd, fpscr, 0, "fdiv");
vdn_nan:
exceptions = vfp_propagate_nan(&vdd, &vdn, &vdm, fpscr);
pack:
vfp_put_double(dd, vfp_double_pack(&vdd));
return exceptions;
vdm_nan:
exceptions = vfp_propagate_nan(&vdd, &vdm, &vdn, fpscr);
goto pack;
zero:
vdd.exponent = 0;
vdd.significand = 0;
goto pack;
divzero:
exceptions = FPSCR_DZC;
infinity:
vdd.exponent = 2047;
vdd.significand = 0;
goto pack;
invalid:
vfp_put_double(dd, vfp_double_pack(&vfp_double_default_qnan));
return FPSCR_IOC;
}
static u32 (* const fop_fns[16])(int dd, int dn, int dm, u32 fpscr) = {
[FOP_TO_IDX(FOP_FMAC)] = vfp_double_fmac,
[FOP_TO_IDX(FOP_FNMAC)] = vfp_double_fnmac,
[FOP_TO_IDX(FOP_FMSC)] = vfp_double_fmsc,
[FOP_TO_IDX(FOP_FNMSC)] = vfp_double_fnmsc,
[FOP_TO_IDX(FOP_FMUL)] = vfp_double_fmul,
[FOP_TO_IDX(FOP_FNMUL)] = vfp_double_fnmul,
[FOP_TO_IDX(FOP_FADD)] = vfp_double_fadd,
[FOP_TO_IDX(FOP_FSUB)] = vfp_double_fsub,
[FOP_TO_IDX(FOP_FDIV)] = vfp_double_fdiv,
};
#define FREG_BANK(x) ((x) & 0x0c)
#define FREG_IDX(x) ((x) & 3)
u32 vfp_double_cpdo(u32 inst, u32 fpscr)
{
u32 op = inst & FOP_MASK;
u32 exceptions = 0;
unsigned int dd = vfp_get_dd(inst);
unsigned int dn = vfp_get_dn(inst);
unsigned int dm = vfp_get_dm(inst);
unsigned int vecitr, veclen, vecstride;
u32 (*fop)(int, int, s32, u32);
veclen = fpscr & FPSCR_LENGTH_MASK;
vecstride = (1 + ((fpscr & FPSCR_STRIDE_MASK) == FPSCR_STRIDE_MASK)) * 2;
/*
* If destination bank is zero, vector length is always '1'.
* ARM DDI0100F C5.1.3, C5.3.2.
*/
if (FREG_BANK(dd) == 0)
veclen = 0;
pr_debug("VFP: vecstride=%u veclen=%u\n", vecstride,
(veclen >> FPSCR_LENGTH_BIT) + 1);
fop = (op == FOP_EXT) ? fop_extfns[FEXT_TO_IDX(inst)] : fop_fns[FOP_TO_IDX(op)];
if (!fop)
goto invalid;
for (vecitr = 0; vecitr <= veclen; vecitr += 1 << FPSCR_LENGTH_BIT) {
u32 except;
if (op == FOP_EXT)
pr_debug("VFP: itr%d (d%u) = op[%u] (d%u)\n",
vecitr >> FPSCR_LENGTH_BIT,
dd, dn, dm);
else
pr_debug("VFP: itr%d (d%u) = (d%u) op[%u] (d%u)\n",
vecitr >> FPSCR_LENGTH_BIT,
dd, dn, FOP_TO_IDX(op), dm);
except = fop(dd, dn, dm, fpscr);
pr_debug("VFP: itr%d: exceptions=%08x\n",
vecitr >> FPSCR_LENGTH_BIT, except);
exceptions |= except;
/*
* This ensures that comparisons only operate on scalars;
* comparisons always return with one FPSCR status bit set.
*/
if (except & (FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V))
break;
/*
* CHECK: It appears to be undefined whether we stop when
* we encounter an exception. We continue.
*/
dd = FREG_BANK(dd) + ((FREG_IDX(dd) + vecstride) & 6);
dn = FREG_BANK(dn) + ((FREG_IDX(dn) + vecstride) & 6);
if (FREG_BANK(dm) != 0)
dm = FREG_BANK(dm) + ((FREG_IDX(dm) + vecstride) & 6);
}
return exceptions;
invalid:
return ~0;
}
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