summaryrefslogtreecommitdiff
path: root/src/arch/x86/isa/decoder/x87.isa
diff options
context:
space:
mode:
authorAndreas Sandberg <andreas@sandberg.pp.se>2013-09-30 12:00:20 +0200
committerAndreas Sandberg <andreas@sandberg.pp.se>2013-09-30 12:00:20 +0200
commit654d1e675a3dc1f598aeadb0824bdb3357820a59 (patch)
treee249108fcd6737dda985b993c95d926a33abca21 /src/arch/x86/isa/decoder/x87.isa
parentc299dcedc6d73aab56d9c659623d7112c2e9c4bb (diff)
downloadgem5-654d1e675a3dc1f598aeadb0824bdb3357820a59.tar.xz
x86: Add support for loading 32-bit and 80-bit floats in the x87
The x87 FPU supports three floating point formats: 32-bit, 64-bit, and 80-bit floats. The current gem5 implementation supports 32-bit and 64-bit floats, but only works correctly for 64-bit floats. This changeset fixes the 32-bit float handling by correctly loading and rounding (using truncation) 32-bit floats instead of simply truncating the bit pattern. 80-bit floats are loaded by first loading the 80-bits of the float to two temporary integer registers. A micro-op (cvtint_fp80) then converts the contents of the two integer registers to the internal FP representation (double). Similarly, when storing an 80-bit float, there are two conversion routines (ctvfp80h_int and cvtfp80l_int) that convert an internal FP register to 80-bit and stores the upper 64-bits or lower 32-bits to an integer register, which is the written to memory using normal integer stores.
Diffstat (limited to 'src/arch/x86/isa/decoder/x87.isa')
-rw-r--r--src/arch/x86/isa/decoder/x87.isa8
1 files changed, 4 insertions, 4 deletions
diff --git a/src/arch/x86/isa/decoder/x87.isa b/src/arch/x86/isa/decoder/x87.isa
index c29e8a334..03ca8be07 100644
--- a/src/arch/x86/isa/decoder/x87.isa
+++ b/src/arch/x86/isa/decoder/x87.isa
@@ -67,11 +67,11 @@ format WarnUnimpl {
0x0: fnop();
default: Inst::UD2();
}
- default: fst();
+ default: Inst::FST(Ed);
}
0x3: decode MODRM_MOD {
0x3: Inst::UD2();
- default: fstp();
+ default: Inst::FSTP(Ed);
}
0x4: decode MODRM_MOD {
0x3: decode MODRM_RM {
@@ -189,7 +189,7 @@ format WarnUnimpl {
0x5: decode MODRM_MOD {
0x3: fucomi();
// 80-bit load
- default: fld();
+ default: Inst::FLD80(M);
}
0x6: decode MODRM_MOD {
0x3: fcomi();
@@ -197,7 +197,7 @@ format WarnUnimpl {
}
0x7: decode MODRM_MOD {
0x3: Inst::UD2();
- default: fstp();
+ default: Inst::FST80P(M);
}
}
//0x4: esc4();