--- /dev/null
+"""SVP64 EXTRA field decoder
+"""
+
+from nmigen import Module, Elaboratable, Signal, Mux, Const, Cat
+from nmigen.cli import rtlil
+from nmutil.util import sel
+
+
+from soc.decoder.power_enums import (SVEXTRA, SVEtype)
+from soc.consts import (SPEC, EXTRA2, EXTRA3, SVP64P, field,
+ SPEC_SIZE, SPECb, SPEC_AUG_SIZE, SVP64CROffs)
+
+
+class SVP64ExtraSpec(Elaboratable):
+ """SVP64ExtraSpec - decodes SVP64 Extra specification.
+
+ selects the required EXTRA2/3 field.
+
+ see https://libre-soc.org/openpower/sv/svp64/
+ """
+ def __init__(self):
+ self.extra = Signal(9, reset_less=True)
+ self.etype = Signal(SVEtype, reset_less=True) # 2 or 3 bits
+ self.idx = Signal(SVEXTRA, reset_less=True) # which part of extra
+ self.spec = Signal(3) # EXTRA spec for the register
+
+ def elaborate(self, platform):
+ m = Module()
+ comb = m.d.comb
+ spec = self.spec
+ extra = self.extra
+
+ # back in the LDSTRM-* and RM-* files generated by sv_analysis.py
+ # we marked every op with an Etype: EXTRA2 or EXTRA3, and also said
+ # which of the 4 (or 3 for EXTRA3) sub-fields of bits 10:18 contain
+ # the register-extension information. extract those now
+ with m.Switch(self.etype):
+ # 2-bit index selection mode
+ with m.Case(SVEtype.EXTRA2):
+ with m.Switch(self.idx):
+ with m.Case(SVEXTRA.Idx0): # 1st 2 bits [0:1]
+ comb += spec[SPEC.VEC].eq(extra[EXTRA2.IDX0_VEC])
+ comb += spec[SPEC.MSB].eq(extra[EXTRA2.IDX0_MSB])
+ with m.Case(SVEXTRA.Idx1): # 2nd 2 bits [2:3]
+ comb += spec[SPEC.VEC].eq(extra[EXTRA2.IDX1_VEC])
+ comb += spec[SPEC.MSB].eq(extra[EXTRA2.IDX1_MSB])
+ with m.Case(SVEXTRA.Idx2): # 3rd 2 bits [4:5]
+ comb += spec[SPEC.VEC].eq(extra[EXTRA2.IDX2_VEC])
+ comb += spec[SPEC.MSB].eq(extra[EXTRA2.IDX2_MSB])
+ with m.Case(SVEXTRA.Idx3): # 4th 2 bits [6:7]
+ comb += spec[SPEC.VEC].eq(extra[EXTRA2.IDX3_VEC])
+ comb += spec[SPEC.MSB].eq(extra[EXTRA2.IDX3_MSB])
+ # 3-bit index selection mode
+ with m.Case(SVEtype.EXTRA3):
+ with m.Switch(self.idx):
+ with m.Case(SVEXTRA.Idx0): # 1st 3 bits [0:2]
+ extra3_idx0 = sel(m, extra, EXTRA3.IDX0)
+ comb += spec.eq(extra3_idx0)
+ with m.Case(SVEXTRA.Idx1): # 2nd 3 bits [3:5]
+ extra3_idx1 = sel(m, extra, EXTRA3.IDX1)
+ comb += spec.eq(extra3_idx1)
+ with m.Case(SVEXTRA.Idx2): # 3rd 3 bits [6:8]
+ extra3_idx2 = sel(m, extra, EXTRA3.IDX2)
+ comb += spec.eq(extra3_idx2)
+ # cannot fit more than 9 bits so there is no 4th thing
+
+ return m
+
+
+class SVP64RegExtra(SVP64ExtraSpec):
+ """SVP64RegExtra - decodes SVP64 Extra fields to determine reg extension
+
+ incoming 5-bit GPR/FP is turned into a 7-bit and marked as scalar/vector
+ depending on info in one of the positions in the EXTRA field.
+
+ designed so that "no change" to the 5-bit register number occurs if
+ SV either does not apply or the relevant EXTRA2/3 field bits are zero.
+
+ see https://libre-soc.org/openpower/sv/svp64/
+ """
+ def __init__(self):
+ SVP64ExtraSpec.__init__(self)
+ self.reg_in = Signal(5) # incoming reg number (5 bits, RA, RB)
+ self.reg_out = Signal(7) # extra-augmented output (7 bits)
+ self.isvec = Signal(1) # reg is marked as vector if true
+
+ def elaborate(self, platform):
+ m = super().elaborate(platform) # select required EXTRA2/3
+ comb = m.d.comb
+
+ # first get the spec. if not changed it's "scalar identity behaviour"
+ # which is zero which is ok.
+ spec = self.spec
+
+ # now decode it. bit 0 is "scalar/vector". note that spec could be zero
+ # from above, which (by design) has the effect of "no change", below.
+
+ # simple: isvec is top bit of spec
+ comb += self.isvec.eq(spec[SPEC.VEC])
+ # extra bits for register number augmentation
+ spec_aug = Signal(SPEC_AUG_SIZE)
+ comb += spec_aug.eq(field(spec, SPECb.MSB, SPECb.LSB, SPEC_SIZE))
+
+ # decode vector differently from scalar
+ with m.If(self.isvec):
+ # Vector: shifted up, extra in LSBs (RA << 2) | spec[1:2]
+ comb += self.reg_out.eq(Cat(spec_aug, self.reg_in))
+ with m.Else():
+ # Scalar: not shifted up, extra in MSBs RA | (spec[1:2] << 5)
+ comb += self.reg_out.eq(Cat(self.reg_in, spec_aug))
+
+ return m
+
+
+class SVP64CRExtra(SVP64ExtraSpec):
+ """SVP64CRExtra - decodes SVP64 Extra fields to determine CR extension
+
+ incoming 3-bit CR is turned into a 7-bit and marked as scalar/vector
+ depending on info in one of the positions in the EXTRA field.
+
+ yes, really, 128 CRs. INT is 128, FP is 128, therefore CRs are 128.
+
+ designed so that "no change" to the 3-bit CR register number occurs if
+ SV either does not apply or the relevant EXTRA2/3 field bits are zero.
+
+ see https://libre-soc.org/openpower/sv/svp64/appendix
+ """
+ def __init__(self):
+ SVP64ExtraSpec.__init__(self)
+ self.cr_in = Signal(3) # incoming CR number (3 bits, BA[0:2], BFA)
+ self.cr_out = Signal(7) # extra-augmented CR output (7 bits)
+ self.isvec = Signal(1) # reg is marked as vector if true
+
+ def elaborate(self, platform):
+ m = super().elaborate(platform) # select required EXTRA2/3
+ comb = m.d.comb
+
+ # first get the spec. if not changed it's "scalar identity behaviour"
+ # which is zero which is ok.
+ spec = self.spec
+
+ # now decode it. bit 0 is "scalar/vector". note that spec could be zero
+ # from above, which (by design) has the effect of "no change", below.
+
+ # simple: isvec is top bit of spec
+ comb += self.isvec.eq(spec[SPEC.VEC])
+ # extra bits for register number augmentation
+ spec_aug = Signal(SPEC_AUG_SIZE)
+ comb += spec_aug.eq(field(spec, SPECb.MSB, SPECb.LSB, SPEC_SIZE))
+
+ # decode vector differently from scalar, insert bits 1 and 2 accordingly
+ with m.If(self.isvec):
+ # Vector: shifted up, extra in LSBs (CR << 4) | (spec[1:2] << 2)
+ comb += self.cr_out.eq(Cat(Const(0, 2), spec_aug, self.cr_in))
+ with m.Else():
+ # Scalar: not shifted up, extra in MSBs CR | (spec[1:2] << 3)
+ comb += self.cr_out.eq(Cat(self.cr_in, spec_aug))
+
+ return m
+
+
+if __name__ == '__main__':
+ pdecode = create_pdecode()
+ dec2 = PowerDecode2(pdecode)
+ vl = rtlil.convert(dec2, ports=dec2.ports() + pdecode.ports())
+ with open("dec2.il", "w") as f:
+ f.write(vl)
projects / soc.git / blobdiff