leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity
35e0be88c4
linux/arch/arm/vfp/vfpdouble.c
Jay Foad 244b478386 ARM: 8026/1: Fix emulation of multiply accumulate instructions 
The emulation for single and double precision multiply accumulate
instructions correctly normalised any denormal values in the operand
registers, but failed to normalise the destination (accumulator)
register.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=70501

Signed-off-by: Jay Foad <jay.foad@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-04-14 23:28:24 +01:00

1207 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/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 = 63 - 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(d, dd);
}
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(vfp_double_packed_abs(vfp_get_double(dm)), dd);
return 0;
}
static u32 vfp_double_fcpy(int dd, int unused, int dm, u32 fpscr)
{
vfp_put_double(vfp_get_double(dm), dd);
return 0;
}
static u32 vfp_double_fneg(int dd, int unused, int dm, u32 fpscr)
{
vfp_put_double(vfp_double_packed_negate(vfp_get_double(dm)), dd);
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(vfp_double_pack(vdp), dd);
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_QNAN)
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(vfp_single_pack(&vsd), sd);
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(d, sd);
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((s32)d, sd);
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 struct op fops_ext[32] = {
[FEXT_TO_IDX(FEXT_FCPY)] = { vfp_double_fcpy, 0 },
[FEXT_TO_IDX(FEXT_FABS)] = { vfp_double_fabs, 0 },
[FEXT_TO_IDX(FEXT_FNEG)] = { vfp_double_fneg, 0 },
[FEXT_TO_IDX(FEXT_FSQRT)] = { vfp_double_fsqrt, 0 },
[FEXT_TO_IDX(FEXT_FCMP)] = { vfp_double_fcmp, OP_SCALAR },
[FEXT_TO_IDX(FEXT_FCMPE)] = { vfp_double_fcmpe, OP_SCALAR },
[FEXT_TO_IDX(FEXT_FCMPZ)] = { vfp_double_fcmpz, OP_SCALAR },
[FEXT_TO_IDX(FEXT_FCMPEZ)] = { vfp_double_fcmpez, OP_SCALAR },
[FEXT_TO_IDX(FEXT_FCVT)] = { vfp_double_fcvts, OP_SCALAR|OP_SD },
[FEXT_TO_IDX(FEXT_FUITO)] = { vfp_double_fuito, OP_SCALAR|OP_SM },
[FEXT_TO_IDX(FEXT_FSITO)] = { vfp_double_fsito, OP_SCALAR|OP_SM },
[FEXT_TO_IDX(FEXT_FTOUI)] = { vfp_double_ftoui, OP_SCALAR|OP_SD },
[FEXT_TO_IDX(FEXT_FTOUIZ)] = { vfp_double_ftouiz, OP_SCALAR|OP_SD },
[FEXT_TO_IDX(FEXT_FTOSI)] = { vfp_double_ftosi, OP_SCALAR|OP_SD },
[FEXT_TO_IDX(FEXT_FTOSIZ)] = { vfp_double_ftosiz, OP_SCALAR|OP_SD },
};
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 (vdn.exponent == 0 && vdn.significand)
vfp_double_normalise_denormal(&vdn);
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(vfp_double_pack(&vdd), dd);
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(vfp_double_pack(&vfp_double_default_qnan), dd);
return FPSCR_IOC;
}
static struct op fops[16] = {
[FOP_TO_IDX(FOP_FMAC)] = { vfp_double_fmac, 0 },
[FOP_TO_IDX(FOP_FNMAC)] = { vfp_double_fnmac, 0 },
[FOP_TO_IDX(FOP_FMSC)] = { vfp_double_fmsc, 0 },
[FOP_TO_IDX(FOP_FNMSC)] = { vfp_double_fnmsc, 0 },
[FOP_TO_IDX(FOP_FMUL)] = { vfp_double_fmul, 0 },
[FOP_TO_IDX(FOP_FNMUL)] = { vfp_double_fnmul, 0 },
[FOP_TO_IDX(FOP_FADD)] = { vfp_double_fadd, 0 },
[FOP_TO_IDX(FOP_FSUB)] = { vfp_double_fsub, 0 },
[FOP_TO_IDX(FOP_FDIV)] = { vfp_double_fdiv, 0 },
};
#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 dest;
unsigned int dn = vfp_get_dn(inst);
unsigned int dm;
unsigned int vecitr, veclen, vecstride;
struct op *fop;
vecstride = (1 + ((fpscr & FPSCR_STRIDE_MASK) == FPSCR_STRIDE_MASK));
fop = (op == FOP_EXT) ? &fops_ext[FEXT_TO_IDX(inst)] : &fops[FOP_TO_IDX(op)];
/*
* fcvtds takes an sN register number as destination, not dN.
* It also always operates on scalars.
*/
if (fop->flags & OP_SD)
dest = vfp_get_sd(inst);
else
dest = vfp_get_dd(inst);
/*
* f[us]ito takes a sN operand, not a dN operand.
*/
if (fop->flags & OP_SM)
dm = vfp_get_sm(inst);
else
dm = vfp_get_dm(inst);
/*
* If destination bank is zero, vector length is always '1'.
* ARM DDI0100F C5.1.3, C5.3.2.
*/
if ((fop->flags & OP_SCALAR) || (FREG_BANK(dest) == 0))
veclen = 0;
else
veclen = fpscr & FPSCR_LENGTH_MASK;
pr_debug("VFP: vecstride=%u veclen=%u\n", vecstride,
(veclen >> FPSCR_LENGTH_BIT) + 1);
if (!fop->fn)
goto invalid;
for (vecitr = 0; vecitr <= veclen; vecitr += 1 << FPSCR_LENGTH_BIT) {
u32 except;
char type;
type = fop->flags & OP_SD ? 's' : 'd';
if (op == FOP_EXT)
pr_debug("VFP: itr%d (%c%u) = op[%u] (d%u)\n",
vecitr >> FPSCR_LENGTH_BIT,
type, dest, dn, dm);
else
pr_debug("VFP: itr%d (%c%u) = (d%u) op[%u] (d%u)\n",
vecitr >> FPSCR_LENGTH_BIT,
type, dest, dn, FOP_TO_IDX(op), dm);
except = fop->fn(dest, dn, dm, fpscr);
pr_debug("VFP: itr%d: exceptions=%08x\n",
vecitr >> FPSCR_LENGTH_BIT, except);
exceptions |= except;
/*
* CHECK: It appears to be undefined whether we stop when
* we encounter an exception. We continue.
*/
dest = FREG_BANK(dest) + ((FREG_IDX(dest) + vecstride) & 3);
dn = FREG_BANK(dn) + ((FREG_IDX(dn) + vecstride) & 3);
if (FREG_BANK(dm) != 0)
dm = FREG_BANK(dm) + ((FREG_IDX(dm) + vecstride) & 3);
}
return exceptions;
invalid:
return ~0;
}
Reference in New Issue View Git Blame Copy Permalink