forked from Minki/linux
m68k/math-emu: Remove commented out old code
It's been unused for ages, and contains bugs (e.g. incorrect shifts in lsl64()). Reported-by: Jonathan Elchison <jelchison@gmail.com> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
This commit is contained in:
Geert Uytterhoeven
parent
b2cb92417d
commit
ffe6c42aa3
@ -19,246 +19,6 @@
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#ifndef MULTI_ARITH_H
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#define MULTI_ARITH_H
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#if 0 /* old code... */
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/* Unsigned only, because we don't need signs to multiply and divide. */
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typedef unsigned int int128[4];
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/* Word order */
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enum {
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MSW128,
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NMSW128,
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NLSW128,
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LSW128
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};
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/* big-endian */
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#define LO_WORD(ll) (((unsigned int *) &ll)[1])
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#define HI_WORD(ll) (((unsigned int *) &ll)[0])
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/* Convenience functions to stuff various integer values into int128s */
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static inline void zero128(int128 a)
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{
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a[LSW128] = a[NLSW128] = a[NMSW128] = a[MSW128] = 0;
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}
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/* Human-readable word order in the arguments */
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static inline void set128(unsigned int i3, unsigned int i2, unsigned int i1,
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unsigned int i0, int128 a)
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{
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a[LSW128] = i0;
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a[NLSW128] = i1;
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a[NMSW128] = i2;
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a[MSW128] = i3;
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}
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/* Convenience functions (for testing as well) */
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static inline void int64_to_128(unsigned long long src, int128 dest)
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{
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dest[LSW128] = (unsigned int) src;
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dest[NLSW128] = src >> 32;
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dest[NMSW128] = dest[MSW128] = 0;
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}
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static inline void int128_to_64(const int128 src, unsigned long long *dest)
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{
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*dest = src[LSW128] | (long long) src[NLSW128] << 32;
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}
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static inline void put_i128(const int128 a)
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{
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printk("%08x %08x %08x %08x\n", a[MSW128], a[NMSW128],
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a[NLSW128], a[LSW128]);
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}
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/* Internal shifters:
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Note that these are only good for 0 < count < 32.
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*/
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static inline void _lsl128(unsigned int count, int128 a)
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{
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a[MSW128] = (a[MSW128] << count) | (a[NMSW128] >> (32 - count));
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a[NMSW128] = (a[NMSW128] << count) | (a[NLSW128] >> (32 - count));
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a[NLSW128] = (a[NLSW128] << count) | (a[LSW128] >> (32 - count));
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a[LSW128] <<= count;
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}
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static inline void _lsr128(unsigned int count, int128 a)
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{
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a[LSW128] = (a[LSW128] >> count) | (a[NLSW128] << (32 - count));
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a[NLSW128] = (a[NLSW128] >> count) | (a[NMSW128] << (32 - count));
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a[NMSW128] = (a[NMSW128] >> count) | (a[MSW128] << (32 - count));
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a[MSW128] >>= count;
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}
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/* Should be faster, one would hope */
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static inline void lslone128(int128 a)
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{
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asm volatile ("lsl.l #1,%0\n"
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"roxl.l #1,%1\n"
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"roxl.l #1,%2\n"
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"roxl.l #1,%3\n"
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:
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"=d" (a[LSW128]),
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"=d"(a[NLSW128]),
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"=d"(a[NMSW128]),
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"=d"(a[MSW128])
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:
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"0"(a[LSW128]),
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"1"(a[NLSW128]),
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"2"(a[NMSW128]),
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"3"(a[MSW128]));
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}
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static inline void lsrone128(int128 a)
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{
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asm volatile ("lsr.l #1,%0\n"
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"roxr.l #1,%1\n"
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"roxr.l #1,%2\n"
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"roxr.l #1,%3\n"
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:
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"=d" (a[MSW128]),
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"=d"(a[NMSW128]),
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"=d"(a[NLSW128]),
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"=d"(a[LSW128])
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:
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"0"(a[MSW128]),
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"1"(a[NMSW128]),
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"2"(a[NLSW128]),
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"3"(a[LSW128]));
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}
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/* Generalized 128-bit shifters:
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These bit-shift to a multiple of 32, then move whole longwords. */
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static inline void lsl128(unsigned int count, int128 a)
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{
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int wordcount, i;
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if (count % 32)
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_lsl128(count % 32, a);
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if (0 == (wordcount = count / 32))
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return;
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/* argh, gak, endian-sensitive */
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for (i = 0; i < 4 - wordcount; i++) {
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a[i] = a[i + wordcount];
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}
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for (i = 3; i >= 4 - wordcount; --i) {
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a[i] = 0;
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}
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}
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static inline void lsr128(unsigned int count, int128 a)
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{
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int wordcount, i;
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if (count % 32)
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_lsr128(count % 32, a);
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if (0 == (wordcount = count / 32))
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return;
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for (i = 3; i >= wordcount; --i) {
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a[i] = a[i - wordcount];
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}
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for (i = 0; i < wordcount; i++) {
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a[i] = 0;
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}
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}
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static inline int orl128(int a, int128 b)
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{
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b[LSW128] |= a;
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}
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static inline int btsthi128(const int128 a)
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{
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return a[MSW128] & 0x80000000;
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}
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/* test bits (numbered from 0 = LSB) up to and including "top" */
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static inline int bftestlo128(int top, const int128 a)
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{
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int r = 0;
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if (top > 31)
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r |= a[LSW128];
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if (top > 63)
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r |= a[NLSW128];
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if (top > 95)
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r |= a[NMSW128];
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r |= a[3 - (top / 32)] & ((1 << (top % 32 + 1)) - 1);
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return (r != 0);
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}
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/* Aargh. We need these because GCC is broken */
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/* FIXME: do them in assembly, for goodness' sake! */
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static inline void mask64(int pos, unsigned long long *mask)
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{
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*mask = 0;
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if (pos < 32) {
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LO_WORD(*mask) = (1 << pos) - 1;
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return;
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}
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LO_WORD(*mask) = -1;
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HI_WORD(*mask) = (1 << (pos - 32)) - 1;
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}
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static inline void bset64(int pos, unsigned long long *dest)
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{
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/* This conditional will be optimized away. Thanks, GCC! */
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if (pos < 32)
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asm volatile ("bset %1,%0":"=m"
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(LO_WORD(*dest)):"id"(pos));
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else
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asm volatile ("bset %1,%0":"=m"
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(HI_WORD(*dest)):"id"(pos - 32));
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}
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static inline int btst64(int pos, unsigned long long dest)
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{
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if (pos < 32)
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return (0 != (LO_WORD(dest) & (1 << pos)));
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else
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return (0 != (HI_WORD(dest) & (1 << (pos - 32))));
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}
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static inline void lsl64(int count, unsigned long long *dest)
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{
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if (count < 32) {
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HI_WORD(*dest) = (HI_WORD(*dest) << count)
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| (LO_WORD(*dest) >> count);
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LO_WORD(*dest) <<= count;
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return;
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}
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count -= 32;
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HI_WORD(*dest) = LO_WORD(*dest) << count;
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LO_WORD(*dest) = 0;
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}
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static inline void lsr64(int count, unsigned long long *dest)
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{
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if (count < 32) {
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LO_WORD(*dest) = (LO_WORD(*dest) >> count)
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| (HI_WORD(*dest) << (32 - count));
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HI_WORD(*dest) >>= count;
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return;
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}
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count -= 32;
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LO_WORD(*dest) = HI_WORD(*dest) >> count;
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HI_WORD(*dest) = 0;
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}
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#endif
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static inline void fp_denormalize(struct fp_ext *reg, unsigned int cnt)
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{
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reg->exp += cnt;
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@ -481,117 +241,6 @@ static inline void fp_dividemant(union fp_mant128 *dest, struct fp_ext *src,
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}
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}
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#if 0
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static inline unsigned int fp_fls128(union fp_mant128 *src)
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{
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unsigned long data;
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unsigned int res, off;
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if ((data = src->m32[0]))
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off = 0;
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else if ((data = src->m32[1]))
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off = 32;
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else if ((data = src->m32[2]))
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off = 64;
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else if ((data = src->m32[3]))
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off = 96;
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else
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return 128;
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asm ("bfffo %1{#0,#32},%0" : "=d" (res) : "dm" (data));
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return res + off;
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}
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static inline void fp_shiftmant128(union fp_mant128 *src, int shift)
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{
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unsigned long sticky;
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switch (shift) {
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case 0:
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return;
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case 1:
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asm volatile ("lsl.l #1,%0"
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: "=d" (src->m32[3]) : "0" (src->m32[3]));
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asm volatile ("roxl.l #1,%0"
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: "=d" (src->m32[2]) : "0" (src->m32[2]));
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asm volatile ("roxl.l #1,%0"
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: "=d" (src->m32[1]) : "0" (src->m32[1]));
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asm volatile ("roxl.l #1,%0"
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: "=d" (src->m32[0]) : "0" (src->m32[0]));
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return;
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case 2 ... 31:
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src->m32[0] = (src->m32[0] << shift) | (src->m32[1] >> (32 - shift));
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src->m32[1] = (src->m32[1] << shift) | (src->m32[2] >> (32 - shift));
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src->m32[2] = (src->m32[2] << shift) | (src->m32[3] >> (32 - shift));
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src->m32[3] = (src->m32[3] << shift);
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return;
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case 32 ... 63:
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shift -= 32;
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src->m32[0] = (src->m32[1] << shift) | (src->m32[2] >> (32 - shift));
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src->m32[1] = (src->m32[2] << shift) | (src->m32[3] >> (32 - shift));
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src->m32[2] = (src->m32[3] << shift);
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src->m32[3] = 0;
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return;
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case 64 ... 95:
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shift -= 64;
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src->m32[0] = (src->m32[2] << shift) | (src->m32[3] >> (32 - shift));
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src->m32[1] = (src->m32[3] << shift);
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src->m32[2] = src->m32[3] = 0;
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return;
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case 96 ... 127:
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shift -= 96;
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src->m32[0] = (src->m32[3] << shift);
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src->m32[1] = src->m32[2] = src->m32[3] = 0;
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return;
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case -31 ... -1:
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shift = -shift;
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sticky = 0;
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if (src->m32[3] << (32 - shift))
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sticky = 1;
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src->m32[3] = (src->m32[3] >> shift) | (src->m32[2] << (32 - shift)) | sticky;
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src->m32[2] = (src->m32[2] >> shift) | (src->m32[1] << (32 - shift));
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src->m32[1] = (src->m32[1] >> shift) | (src->m32[0] << (32 - shift));
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src->m32[0] = (src->m32[0] >> shift);
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return;
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case -63 ... -32:
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shift = -shift - 32;
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sticky = 0;
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if ((src->m32[2] << (32 - shift)) || src->m32[3])
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sticky = 1;
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src->m32[3] = (src->m32[2] >> shift) | (src->m32[1] << (32 - shift)) | sticky;
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src->m32[2] = (src->m32[1] >> shift) | (src->m32[0] << (32 - shift));
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src->m32[1] = (src->m32[0] >> shift);
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src->m32[0] = 0;
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return;
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case -95 ... -64:
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shift = -shift - 64;
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sticky = 0;
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if ((src->m32[1] << (32 - shift)) || src->m32[2] || src->m32[3])
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sticky = 1;
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src->m32[3] = (src->m32[1] >> shift) | (src->m32[0] << (32 - shift)) | sticky;
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src->m32[2] = (src->m32[0] >> shift);
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src->m32[1] = src->m32[0] = 0;
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return;
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case -127 ... -96:
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shift = -shift - 96;
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sticky = 0;
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if ((src->m32[0] << (32 - shift)) || src->m32[1] || src->m32[2] || src->m32[3])
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sticky = 1;
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src->m32[3] = (src->m32[0] >> shift) | sticky;
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src->m32[2] = src->m32[1] = src->m32[0] = 0;
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return;
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}
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if (shift < 0 && (src->m32[0] || src->m32[1] || src->m32[2] || src->m32[3]))
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src->m32[3] = 1;
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else
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src->m32[3] = 0;
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src->m32[2] = 0;
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src->m32[1] = 0;
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src->m32[0] = 0;
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}
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#endif
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static inline void fp_putmant128(struct fp_ext *dest, union fp_mant128 *src,
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int shift)
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{
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@ -637,183 +286,4 @@ static inline void fp_putmant128(struct fp_ext *dest, union fp_mant128 *src,
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}
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}
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#if 0 /* old code... */
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static inline int fls(unsigned int a)
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{
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int r;
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asm volatile ("bfffo %1{#0,#32},%0"
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: "=d" (r) : "md" (a));
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return r;
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}
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/* fls = "find last set" (cf. ffs(3)) */
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static inline int fls128(const int128 a)
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{
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if (a[MSW128])
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return fls(a[MSW128]);
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if (a[NMSW128])
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return fls(a[NMSW128]) + 32;
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/* XXX: it probably never gets beyond this point in actual
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use, but that's indicative of a more general problem in the
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algorithm (i.e. as per the actual 68881 implementation, we
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really only need at most 67 bits of precision [plus
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overflow]) so I'm not going to fix it. */
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if (a[NLSW128])
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return fls(a[NLSW128]) + 64;
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if (a[LSW128])
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return fls(a[LSW128]) + 96;
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else
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return -1;
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}
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static inline int zerop128(const int128 a)
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{
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return !(a[LSW128] | a[NLSW128] | a[NMSW128] | a[MSW128]);
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}
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static inline int nonzerop128(const int128 a)
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{
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return (a[LSW128] | a[NLSW128] | a[NMSW128] | a[MSW128]);
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}
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/* Addition and subtraction */
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/* Do these in "pure" assembly, because "extended" asm is unmanageable
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here */
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static inline void add128(const int128 a, int128 b)
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{
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/* rotating carry flags */
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unsigned int carry[2];
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carry[0] = a[LSW128] > (0xffffffff - b[LSW128]);
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b[LSW128] += a[LSW128];
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carry[1] = a[NLSW128] > (0xffffffff - b[NLSW128] - carry[0]);
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b[NLSW128] = a[NLSW128] + b[NLSW128] + carry[0];
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carry[0] = a[NMSW128] > (0xffffffff - b[NMSW128] - carry[1]);
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b[NMSW128] = a[NMSW128] + b[NMSW128] + carry[1];
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b[MSW128] = a[MSW128] + b[MSW128] + carry[0];
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}
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/* Note: assembler semantics: "b -= a" */
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static inline void sub128(const int128 a, int128 b)
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{
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/* rotating borrow flags */
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unsigned int borrow[2];
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borrow[0] = b[LSW128] < a[LSW128];
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b[LSW128] -= a[LSW128];
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borrow[1] = b[NLSW128] < a[NLSW128] + borrow[0];
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b[NLSW128] = b[NLSW128] - a[NLSW128] - borrow[0];
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borrow[0] = b[NMSW128] < a[NMSW128] + borrow[1];
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b[NMSW128] = b[NMSW128] - a[NMSW128] - borrow[1];
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b[MSW128] = b[MSW128] - a[MSW128] - borrow[0];
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}
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||||
/* Poor man's 64-bit expanding multiply */
|
||||
static inline void mul64(unsigned long long a, unsigned long long b, int128 c)
|
||||
{
|
||||
unsigned long long acc;
|
||||
int128 acc128;
|
||||
|
||||
zero128(acc128);
|
||||
zero128(c);
|
||||
|
||||
/* first the low words */
|
||||
if (LO_WORD(a) && LO_WORD(b)) {
|
||||
acc = (long long) LO_WORD(a) * LO_WORD(b);
|
||||
c[NLSW128] = HI_WORD(acc);
|
||||
c[LSW128] = LO_WORD(acc);
|
||||
}
|
||||
/* Next the high words */
|
||||
if (HI_WORD(a) && HI_WORD(b)) {
|
||||
acc = (long long) HI_WORD(a) * HI_WORD(b);
|
||||
c[MSW128] = HI_WORD(acc);
|
||||
c[NMSW128] = LO_WORD(acc);
|
||||
}
|
||||
/* The middle words */
|
||||
if (LO_WORD(a) && HI_WORD(b)) {
|
||||
acc = (long long) LO_WORD(a) * HI_WORD(b);
|
||||
acc128[NMSW128] = HI_WORD(acc);
|
||||
acc128[NLSW128] = LO_WORD(acc);
|
||||
add128(acc128, c);
|
||||
}
|
||||
/* The first and last words */
|
||||
if (HI_WORD(a) && LO_WORD(b)) {
|
||||
acc = (long long) HI_WORD(a) * LO_WORD(b);
|
||||
acc128[NMSW128] = HI_WORD(acc);
|
||||
acc128[NLSW128] = LO_WORD(acc);
|
||||
add128(acc128, c);
|
||||
}
|
||||
}
|
||||
|
||||
/* Note: unsigned */
|
||||
static inline int cmp128(int128 a, int128 b)
|
||||
{
|
||||
if (a[MSW128] < b[MSW128])
|
||||
return -1;
|
||||
if (a[MSW128] > b[MSW128])
|
||||
return 1;
|
||||
if (a[NMSW128] < b[NMSW128])
|
||||
return -1;
|
||||
if (a[NMSW128] > b[NMSW128])
|
||||
return 1;
|
||||
if (a[NLSW128] < b[NLSW128])
|
||||
return -1;
|
||||
if (a[NLSW128] > b[NLSW128])
|
||||
return 1;
|
||||
|
||||
return (signed) a[LSW128] - b[LSW128];
|
||||
}
|
||||
|
||||
inline void div128(int128 a, int128 b, int128 c)
|
||||
{
|
||||
int128 mask;
|
||||
|
||||
/* Algorithm:
|
||||
|
||||
Shift the divisor until it's at least as big as the
|
||||
dividend, keeping track of the position to which we've
|
||||
shifted it, i.e. the power of 2 which we've multiplied it
|
||||
by.
|
||||
|
||||
Then, for this power of 2 (the mask), and every one smaller
|
||||
than it, subtract the mask from the dividend and add it to
|
||||
the quotient until the dividend is smaller than the raised
|
||||
divisor. At this point, divide the dividend and the mask
|
||||
by 2 (i.e. shift one place to the right). Lather, rinse,
|
||||
and repeat, until there are no more powers of 2 left. */
|
||||
|
||||
/* FIXME: needless to say, there's room for improvement here too. */
|
||||
|
||||
/* Shift up */
|
||||
/* XXX: since it just has to be "at least as big", we can
|
||||
probably eliminate this horribly wasteful loop. I will
|
||||
have to prove this first, though */
|
||||
set128(0, 0, 0, 1, mask);
|
||||
while (cmp128(b, a) < 0 && !btsthi128(b)) {
|
||||
lslone128(b);
|
||||
lslone128(mask);
|
||||
}
|
||||
|
||||
/* Shift down */
|
||||
zero128(c);
|
||||
do {
|
||||
if (cmp128(a, b) >= 0) {
|
||||
sub128(b, a);
|
||||
add128(mask, c);
|
||||
}
|
||||
lsrone128(mask);
|
||||
lsrone128(b);
|
||||
} while (nonzerop128(mask));
|
||||
|
||||
/* The remainder is in a... */
|
||||
}
|
||||
#endif
|
||||
|
||||
#endif /* MULTI_ARITH_H */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user