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Diffstat (limited to 'src/arch/alpha/isa/util.isa')
| -rw-r--r-- | src/arch/alpha/isa/util.isa | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/src/arch/alpha/isa/util.isa b/src/arch/alpha/isa/util.isa new file mode 100644 index 000000000..9fbbf6636 --- /dev/null +++ b/src/arch/alpha/isa/util.isa @@ -0,0 +1,112 @@ +// -*- mode:c++ -*- + +// Copyright (c) 2003-2005 The Regents of The University of Michigan +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer; +// redistributions in binary form must reproduce the above copyright +// notice, this list of conditions and the following disclaimer in the +// documentation and/or other materials provided with the distribution; +// neither the name of the copyright holders nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +output exec {{ + + /// Return opa + opb, summing carry into third arg. + inline uint64_t + addc(uint64_t opa, uint64_t opb, int &carry) + { + uint64_t res = opa + opb; + if (res < opa || res < opb) + ++carry; + return res; + } + + /// Multiply two 64-bit values (opa * opb), returning the 128-bit + /// product in res_hi and res_lo. + inline void + mul128(uint64_t opa, uint64_t opb, uint64_t &res_hi, uint64_t &res_lo) + { + // do a 64x64 --> 128 multiply using four 32x32 --> 64 multiplies + uint64_t opa_hi = opa<63:32>; + uint64_t opa_lo = opa<31:0>; + uint64_t opb_hi = opb<63:32>; + uint64_t opb_lo = opb<31:0>; + + res_lo = opa_lo * opb_lo; + + // The middle partial products logically belong in bit + // positions 95 to 32. Thus the lower 32 bits of each product + // sum into the upper 32 bits of the low result, while the + // upper 32 sum into the low 32 bits of the upper result. + uint64_t partial1 = opa_hi * opb_lo; + uint64_t partial2 = opa_lo * opb_hi; + + uint64_t partial1_lo = partial1<31:0> << 32; + uint64_t partial1_hi = partial1<63:32>; + uint64_t partial2_lo = partial2<31:0> << 32; + uint64_t partial2_hi = partial2<63:32>; + + // Add partial1_lo and partial2_lo to res_lo, keeping track + // of any carries out + int carry_out = 0; + res_lo = addc(partial1_lo, res_lo, carry_out); + res_lo = addc(partial2_lo, res_lo, carry_out); + + // Now calculate the high 64 bits... + res_hi = (opa_hi * opb_hi) + partial1_hi + partial2_hi + carry_out; + } + + /// Map 8-bit S-floating exponent to 11-bit T-floating exponent. + /// See Table 2-2 of Alpha AHB. + inline int + map_s(int old_exp) + { + int hibit = old_exp<7:>; + int lobits = old_exp<6:0>; + + if (hibit == 1) { + return (lobits == 0x7f) ? 0x7ff : (0x400 | lobits); + } + else { + return (lobits == 0) ? 0 : (0x380 | lobits); + } + } + + /// Convert a 32-bit S-floating value to the equivalent 64-bit + /// representation to be stored in an FP reg. + inline uint64_t + s_to_t(uint32_t s_val) + { + uint64_t tmp = s_val; + return (tmp<31:> << 63 // sign bit + | (uint64_t)map_s(tmp<30:23>) << 52 // exponent + | tmp<22:0> << 29); // fraction + } + + /// Convert a 64-bit T-floating value to the equivalent 32-bit + /// S-floating representation to be stored in memory. + inline int32_t + t_to_s(uint64_t t_val) + { + return (t_val<63:62> << 30 // sign bit & hi exp bit + | t_val<58:29>); // rest of exp & fraction + } +}}; + |