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target/arm: Split out vfp_expand_imm

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Backports commit e90a99fe6bde9b85bff8c052ade51520f20d9bce from qemu.
This commit is contained in:
Lioncash 2018-02-07 09:44:42 -05:00
parent 4c165ed788
commit b55f35ba92
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GPG key ID: 4E3C3CC1031BA9C7
1 changed files with 28 additions and 16 deletions
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44
qemu/target-arm/translate-a64.c
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@ -4712,6 +4712,33 @@ static void disas_fp_3src(DisasContext *s, uint32_t insn)
}
}
/* The imm8 encodes the sign bit, enough bits to represent an exponent in
* the range 01....1xx to 10....0xx, and the most significant 4 bits of
* the mantissa; see VFPExpandImm() in the v8 ARM ARM.
*/
static uint64_t vfp_expand_imm(int size, uint8_t imm8)
{
uint64_t imm;
switch (size) {
case MO_64:
imm = (extract32(imm8, 7, 1) ? 0x8000 : 0) |
(extract32(imm8, 6, 1) ? 0x3fc0 : 0x4000) |
extract32(imm8, 0, 6);
imm <<= 48;
break;
case MO_32:
imm = (extract32(imm8, 7, 1) ? 0x8000 : 0) |
(extract32(imm8, 6, 1) ? 0x3e00 : 0x4000) |
(extract32(imm8, 0, 6) << 3);
imm <<= 16;
break;
default:
g_assert_not_reached();
}
return imm;
}
/* C3.6.28 Floating point immediate
* 31 30 29 28 24 23 22 21 20 13 12 10 9 5 4 0
* +---+---+---+-----------+------+---+------------+-------+------+------+
@ -4736,22 +4763,7 @@ static void disas_fp_imm(DisasContext *s, uint32_t insn)
return;
}
/* The imm8 encodes the sign bit, enough bits to represent
* an exponent in the range 01....1xx to 10....0xx,
* and the most significant 4 bits of the mantissa; see
* VFPExpandImm() in the v8 ARM ARM.
*/
if (is_double) {
imm = (extract32(imm8, 7, 1) ? 0x8000 : 0) |
(extract32(imm8, 6, 1) ? 0x3fc0 : 0x4000) |
extract32(imm8, 0, 6);
imm <<= 48;
} else {
imm = (extract32(imm8, 7, 1) ? 0x8000 : 0) |
(extract32(imm8, 6, 1) ? 0x3e00 : 0x4000) |
(extract32(imm8, 0, 6) << 3);
imm <<= 16;
}
imm = vfp_expand_imm(MO_32 + is_double, imm8);
tcg_res = tcg_const_i64(tcg_ctx, imm);
write_fp_dreg(s, rd, tcg_res);