target-ppc: Introduce DFP Helper Utilities

Add a new file (dfp_helper.c) to the PowerPC implementation for Decimal Floating
Point (DFP) emulation.  This first version of the file declares a structure that
will be used by DFP helpers.  It also implements utilities that will initialize
such a structure for either a long (64 bit) DFP instruction or an extended (128
bit, aka "quad") instruction.

Some utility functions are annotated with the unused attribute in order to preserve
build bisection.

Signed-off-by: Tom Musta <tommusta@gmail.com>
[agraf: Add never reached assert on dfp_prepare_rounding_mode()]
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Post Processor Utilities

Add post-processing utilities to the PowerPC Decimal Floating Point
(DFP) helper code.  Post-processors are small routines that execute
after a preliminary DFP result is computed.  They are used, among other
things, to compute status bits.

This change defines a function type for post processors as well as a
generic routine to run a list (array) of post-processors.

Actual post-processor implementations will be added as needed by specific
DFP helpers in subsequent changes.

Some routines are annotated with the GCC unused attribute in order to
preserve build bisection.  The annotation will be removed in subsequent
patches.

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Add

Add emulation of the PowerPC Decimal Floating Point Add instructions dadd[q][.]

Various GCC unused annotations are removed since it is now safe to remove them.

Signed-off-by: Tom Musta <tommusta@gmail.com>
[agraf: move brace in function definition]
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Subtract

Add emulation of the PowerPC Decimal Floating Point Subtract instructions
dsub[q][.]

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Multiply

Add emulation of the PowerPC Decimal Floating Point Multiply instructions
dmul[q][.]

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Divide

Add emulation of the PowerPC Decimal Floating Point Divide instructions
ddiv[q][.]

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Compares

Add emulation of the PowerPC Decimal Floating Point Compare instructions
dcmpu[q] and dcmpo[q].

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Test Data Class

Add emulation of the PowerPC Decimal Floating Point Test Data Class
instructions dtstdc[q][.].

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Test Data Group

Add emulation of the PowerPC Decimal Floating Point Test Data
Group instructions dtstdg[q][.].

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Test Exponent

Add emulation of the PowerPC Decimal Floating Point Test Exponent
instructions dtstex[q][.].

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Test Significance

Add emulation of the PowerPC Decimal Floating Point Test Significance
instructions dtstsf[q][.].

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Quantize

Add emulation of the PowerPC Decimal Floating Point Quantize instructions
dquai[q][.] and dqua[q][.].

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Reround

Add emulation of the PowerPC Decimal Floating Point Reround instructions
drrnd[q][.].

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Round to Integer

Add emulation of the PowerPC Decimal Floating Point (DFP) Round
to FP Integer With Inexact (drintx[q][.]) and DFP Round to FP
Integer Without Inexact (drintn[q][.]) instructions.

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Convert to Long/Extended

Add emulation of the PowerPC Convert to DFP Long (dctdp[.]) and
Convert to DFP Extended (dctqpq[.]) instructions.

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce Round to DFP Short/Long

Add emulation of the PowerPC Round to DFP Short (drsp[.]) and Round to
DFP Long (drdpq[.]) instructions.

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Convert to Fixed

Add emulation of the PowerPC Decimal Floating Point Convert to
Fixed instructions dctfix[q][.].

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Convert to Fixed

Add emulation of the PowerPC Decimal Floating Point Convert to Fixed
instructions dctfix[q][.].

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Decode DPD to BCD

Add emulation of the Power PC Decimal Floating Point Decode
Densely Packed Decimal to Binary Coded Decimal instructions
ddedpd[q][.].

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
target-ppc: Introduce DFP Encode BCD to DPD

Add emulation of the PowerPC Decimal Floating Point Encode Binary
Coded Decimal to Densely Packed Decimal instructions denbcd[q][.].

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>