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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* multi_arith.h: multi-precision integer arithmetic functions, needed
to do extended-precision floating point.
(c) 1998 David Huggins-Daines.
Somewhat based on arch/alpha/math-emu/ieee-math.c, which is (c)
David Mosberger-Tang.
*/
/* Note:
These are not general multi-precision math routines. Rather, they
implement the subset of integer arithmetic that we need in order to
multiply, divide, and normalize 128-bit unsigned mantissae. */
#ifndef MULTI_ARITH_H
#define MULTI_ARITH_H
static inline void fp_denormalize(struct fp_ext *reg, unsigned int cnt)
{
reg->exp += cnt;
switch (cnt) {
case 0 ... 8:
reg->lowmant = reg->mant.m32[1] << (8 - cnt);
reg->mant.m32[1] = (reg->mant.m32[1] >> cnt) |
(reg->mant.m32[0] << (32 - cnt));
reg->mant.m32[0] = reg->mant.m32[0] >> cnt;
break;
case 9 ... 32:
reg->lowmant = reg->mant.m32[1] >> (cnt - 8);
if (reg->mant.m32[1] << (40 - cnt))
reg->lowmant |= 1;
reg->mant.m32[1] = (reg->mant.m32[1] >> cnt) |
(reg->mant.m32[0] << (32 - cnt));
reg->mant.m32[0] = reg->mant.m32[0] >> cnt;
break;
case 33 ... 39:
asm volatile ("bfextu %1{%2,#8},%0" : "=d" (reg->lowmant)
: "m" (reg->mant.m32[0]), "d" (64 - cnt));
if (reg->mant.m32[1] << (40 - cnt))
reg->lowmant |= 1;
reg->mant.m32[1] = reg->mant.m32[0] >> (cnt - 32);
reg->mant.m32[0] = 0;
break;
case 40 ... 71:
reg->lowmant = reg->mant.m32[0] >> (cnt - 40);
if ((reg->mant.m32[0] << (72 - cnt)) || reg->mant.m32[1])
reg->lowmant |= 1;
reg->mant.m32[1] = reg->mant.m32[0] >> (cnt - 32);
reg->mant.m32[0] = 0;
break;
default:
reg->lowmant = reg->mant.m32[0] || reg->mant.m32[1];
reg->mant.m32[0] = 0;
reg->mant.m32[1] = 0;
break;
}
}
static inline int fp_overnormalize(struct fp_ext *reg)
{
int shift;
if (reg->mant.m32[0]) {
asm ("bfffo %1{#0,#32},%0" : "=d" (shift) : "dm" (reg->mant.m32[0]));
reg->mant.m32[0] = (reg->mant.m32[0] << shift) | (reg->mant.m32[1] >> (32 - shift));
reg->mant.m32[1] = (reg->mant.m32[1] << shift);
} else {
asm ("bfffo %1{#0,#32},%0" : "=d" (shift) : "dm" (reg->mant.m32[1]));
reg->mant.m32[0] = (reg->mant.m32[1] << shift);
reg->mant.m32[1] = 0;
shift += 32;
}
return shift;
}
static inline int fp_addmant(struct fp_ext *dest, struct fp_ext *src)
{
int carry;
/* we assume here, gcc only insert move and a clr instr */
asm volatile ("add.b %1,%0" : "=d,g" (dest->lowmant)
: "g,d" (src->lowmant), "0,0" (dest->lowmant));
asm volatile ("addx.l %1,%0" : "=d" (dest->mant.m32[1])
: "d" (src->mant.m32[1]), "0" (dest->mant.m32[1]));
asm volatile ("addx.l %1,%0" : "=d" (dest->mant.m32[0])
: "d" (src->mant.m32[0]), "0" (dest->mant.m32[0]));
asm volatile ("addx.l %0,%0" : "=d" (carry) : "0" (0));
return carry;
}
static inline int fp_addcarry(struct fp_ext *reg)
{
if (++reg->exp == 0x7fff) {
if (reg->mant.m64)
fp_set_sr(FPSR_EXC_INEX2);
reg->mant.m64 = 0;
fp_set_sr(FPSR_EXC_OVFL);
return 0;
}
reg->lowmant = (reg->mant.m32[1] << 7) | (reg->lowmant ? 1 : 0);
reg->mant.m32[1] = (reg->mant.m32[1] >> 1) |
(reg->mant.m32[0] << 31);
reg->mant.m32[0] = (reg->mant.m32[0] >> 1) | 0x80000000;
return 1;
}
static inline void fp_submant(struct fp_ext *dest, struct fp_ext *src1,
struct fp_ext *src2)
{
/* we assume here, gcc only insert move and a clr instr */
asm volatile ("sub.b %1,%0" : "=d,g" (dest->lowmant)
: "g,d" (src2->lowmant), "0,0" (src1->lowmant));
asm volatile ("subx.l %1,%0" : "=d" (dest->mant.m32[1])
: "d" (src2->mant.m32[1]), "0" (src1->mant.m32[1]));
asm volatile ("subx.l %1,%0" : "=d" (dest->mant.m32[0])
: "d" (src2->mant.m32[0]), "0" (src1->mant.m32[0]));
}
#define fp_mul64(desth, destl, src1, src2) ({ \
asm ("mulu.l %2,%1:%0" : "=d" (destl), "=d" (desth) \
: "dm" (src1), "0" (src2)); \
})
#define fp_div64(quot, rem, srch, srcl, div) \
asm ("divu.l %2,%1:%0" : "=d" (quot), "=d" (rem) \
: "dm" (div), "1" (srch), "0" (srcl))
#define fp_add64(dest1, dest2, src1, src2) ({ \
asm ("add.l %1,%0" : "=d,dm" (dest2) \
: "dm,d" (src2), "0,0" (dest2)); \
asm ("addx.l %1,%0" : "=d" (dest1) \
: "d" (src1), "0" (dest1)); \
})
#define fp_addx96(dest, src) ({ \
/* we assume here, gcc only insert move and a clr instr */ \
asm volatile ("add.l %1,%0" : "=d,g" (dest->m32[2]) \
: "g,d" (temp.m32[1]), "0,0" (dest->m32[2])); \
asm volatile ("addx.l %1,%0" : "=d" (dest->m32[1]) \
: "d" (temp.m32[0]), "0" (dest->m32[1])); \
asm volatile ("addx.l %1,%0" : "=d" (dest->m32[0]) \
: "d" (0), "0" (dest->m32[0])); \
})
#define fp_sub64(dest, src) ({ \
asm ("sub.l %1,%0" : "=d,dm" (dest.m32[1]) \
: "dm,d" (src.m32[1]), "0,0" (dest.m32[1])); \
asm ("subx.l %1,%0" : "=d" (dest.m32[0]) \
: "d" (src.m32[0]), "0" (dest.m32[0])); \
})
#define fp_sub96c(dest, srch, srcm, srcl) ({ \
char carry; \
asm ("sub.l %1,%0" : "=d,dm" (dest.m32[2]) \
: "dm,d" (srcl), "0,0" (dest.m32[2])); \
asm ("subx.l %1,%0" : "=d" (dest.m32[1]) \
: "d" (srcm), "0" (dest.m32[1])); \
asm ("subx.l %2,%1; scs %0" : "=d" (carry), "=d" (dest.m32[0]) \
: "d" (srch), "1" (dest.m32[0])); \
carry; \
})
static inline void fp_multiplymant(union fp_mant128 *dest, struct fp_ext *src1,
struct fp_ext *src2)
{
union fp_mant64 temp;
fp_mul64(dest->m32[0], dest->m32[1], src1->mant.m32[0], src2->mant.m32[0]);
fp_mul64(dest->m32[2], dest->m32[3], src1->mant.m32[1], src2->mant.m32[1]);
fp_mul64(temp.m32[0], temp.m32[1], src1->mant.m32[0], src2->mant.m32[1]);
fp_addx96(dest, temp);
fp_mul64(temp.m32[0], temp.m32[1], src1->mant.m32[1], src2->mant.m32[0]);
fp_addx96(dest, temp);
}
static inline void fp_dividemant(union fp_mant128 *dest, struct fp_ext *src,
struct fp_ext *div)
{
union fp_mant128 tmp;
union fp_mant64 tmp64;
unsigned long *mantp = dest->m32;
unsigned long fix, rem, first, dummy;
int i;
/* the algorithm below requires dest to be smaller than div,
but both have the high bit set */
if (src->mant.m64 >= div->mant.m64) {
fp_sub64(src->mant, div->mant);
*mantp = 1;
} else
*mantp = 0;
mantp++;
/* basic idea behind this algorithm: we can't divide two 64bit numbers
(AB/CD) directly, but we can calculate AB/C0, but this means this
quotient is off by C0/CD, so we have to multiply the first result
to fix the result, after that we have nearly the correct result
and only a few corrections are needed. */
/* C0/CD can be precalculated, but it's an 64bit division again, but
we can make it a bit easier, by dividing first through C so we get
10/1D and now only a single shift and the value fits into 32bit. */
fix = 0x80000000;
dummy = div->mant.m32[1] / div->mant.m32[0] + 1;
dummy = (dummy >> 1) | fix;
fp_div64(fix, dummy, fix, 0, dummy);
fix--;
for (i = 0; i < 3; i++, mantp++) {
if (src->mant.m32[0] == div->mant.m32[0]) {
fp_div64(first, rem, 0, src->mant.m32[1], div->mant.m32[0]);
fp_mul64(*mantp, dummy, first, fix);
*mantp += fix;
} else {
fp_div64(first, rem, src->mant.m32[0], src->mant.m32[1], div->mant.m32[0]);
fp_mul64(*mantp, dummy, first, fix);
}
fp_mul64(tmp.m32[0], tmp.m32[1], div->mant.m32[0], first - *mantp);
fp_add64(tmp.m32[0], tmp.m32[1], 0, rem);
tmp.m32[2] = 0;
fp_mul64(tmp64.m32[0], tmp64.m32[1], *mantp, div->mant.m32[1]);
fp_sub96c(tmp, 0, tmp64.m32[0], tmp64.m32[1]);
src->mant.m32[0] = tmp.m32[1];
src->mant.m32[1] = tmp.m32[2];
while (!fp_sub96c(tmp, 0, div->mant.m32[0], div->mant.m32[1])) {
src->mant.m32[0] = tmp.m32[1];
src->mant.m32[1] = tmp.m32[2];
*mantp += 1;
}
}
}
static inline void fp_putmant128(struct fp_ext *dest, union fp_mant128 *src,
int shift)
{
unsigned long tmp;
switch (shift) {
case 0:
dest->mant.m64 = src->m64[0];
dest->lowmant = src->m32[2] >> 24;
if (src->m32[3] || (src->m32[2] << 8))
dest->lowmant |= 1;
break;
case 1:
asm volatile ("lsl.l #1,%0"
: "=d" (tmp) : "0" (src->m32[2]));
asm volatile ("roxl.l #1,%0"
: "=d" (dest->mant.m32[1]) : "0" (src->m32[1]));
asm volatile ("roxl.l #1,%0"
: "=d" (dest->mant.m32[0]) : "0" (src->m32[0]));
dest->lowmant = tmp >> 24;
if (src->m32[3] || (tmp << 8))
dest->lowmant |= 1;
break;
case 31:
asm volatile ("lsr.l #1,%1; roxr.l #1,%0"
: "=d" (dest->mant.m32[0])
: "d" (src->m32[0]), "0" (src->m32[1]));
asm volatile ("roxr.l #1,%0"
: "=d" (dest->mant.m32[1]) : "0" (src->m32[2]));
asm volatile ("roxr.l #1,%0"
: "=d" (tmp) : "0" (src->m32[3]));
dest->lowmant = tmp >> 24;
if (src->m32[3] << 7)
dest->lowmant |= 1;
break;
case 32:
dest->mant.m32[0] = src->m32[1];
dest->mant.m32[1] = src->m32[2];
dest->lowmant = src->m32[3] >> 24;
if (src->m32[3] << 8)
dest->lowmant |= 1;
break;
}
}
#endif /* MULTI_ARITH_H */
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