src/arch/arm/isa/formats/branch.isa

// -*- mode:c++ -*-

// Copyright (c) 2010,2012-2013,2017 ARM Limited
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// terms below provided that you ensure that this notice is replicated
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// modified or unmodified, in source code or in binary form.
//
// Copyright (c) 2007-2008 The Florida State University
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// 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;
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// Authors: Stephen Hines

////////////////////////////////////////////////////////////////////
//
// Control transfer instructions
//

def format ArmBBlxImm() {{
    decode_block = '''
        if (machInst.condCode == 0xF) {
            int32_t imm = (sext<26>(bits(machInst, 23, 0) << 2)) |
                          (bits(machInst, 24) << 1);
            return new BlxImm(machInst, imm, COND_UC);
        } else {
            return new B(machInst, sext<26>(bits(machInst, 23, 0) << 2),
                         (ConditionCode)(uint32_t)machInst.condCode);
        }
    '''
}};

def format ArmBlBlxImm() {{
    decode_block = '''
        if (machInst.condCode == 0xF) {
            int32_t imm = (sext<26>(bits(machInst, 23, 0) << 2)) |
                          (bits(machInst, 24) << 1);
            return new BlxImm(machInst, imm, COND_UC);
        } else {
            return new Bl(machInst, sext<26>(bits(machInst, 23, 0) << 2),
                          (ConditionCode)(uint32_t)machInst.condCode);
        }
    '''
}};

def format ArmBxClz() {{
    decode_block = '''
    {
        const IntRegIndex rm = (IntRegIndex)(uint32_t)bits(machInst, 3, 0);
        const IntRegIndex rd = (IntRegIndex)(uint32_t)bits(machInst, 15, 12);
        if (OPCODE == 0x9) {
            return new BxReg(machInst, rm,
                    (ConditionCode)(uint32_t)machInst.condCode);
        } else if (OPCODE == 0xb) {
            return new Clz(machInst, rd, rm);
        } else {
            return new Unknown(machInst);
        }
    }
    '''
}};

def format ArmBlxReg() {{
    decode_block = '''
        return new BlxReg(machInst, (IntRegIndex)(uint32_t)bits(machInst, 3, 0),
                          (ConditionCode)(uint32_t)machInst.condCode);
    '''
}};

def format Thumb16CondBranchAndSvc() {{
    decode_block = '''
        if (bits(machInst, 11, 9) != 0x7) {
            return new B(machInst, sext<9>(bits(machInst, 7, 0) << 1),
                         (ConditionCode)(uint32_t)bits(machInst, 11, 8));
        } else if (bits(machInst, 8)) {
            return new Svc(machInst, bits(machInst, 7, 0));
        } else {
            // This space will not be allocated in the future.
            return new Unknown(machInst);
        }
    '''
}};

def format Thumb16UncondBranch() {{
    decode_block = '''
        return new B(machInst, sext<12>(bits(machInst, 10, 0) << 1), COND_UC);
    '''
}};

def format Thumb32BranchesAndMiscCtrl() {{
    decode_block = '''
    {
        const uint32_t op = bits(machInst, 26, 20);
        const uint32_t op1 = bits(machInst, 14, 12);
        switch (op1 & 0x5) {
          case 0x0:
            if (op == 127) {
                if (op1 & 0x2) {
                    // Permanently undefined.
                    return new Unknown(machInst);
                } else {
                    return new Smc(machInst);
                }
            } else if ((op & 0x38) != 0x38) {
                const uint32_t s = bits(machInst, 26);
                const uint32_t j1 = bits(machInst, 13);
                const uint32_t j2 = bits(machInst, 11);
                const uint32_t imm6 = bits(machInst, 21, 16);
                const uint32_t imm11 = bits(machInst, 10, 0);
                const int32_t imm = sext<21>((s << 20) |
                                             (j2 << 19) | (j1 << 18) |
                                             (imm6 << 12) | (imm11 << 1));
                return new B(machInst, imm,
                             (ConditionCode)(uint32_t)bits(machInst, 25, 22));
            } else {
                // HIGH: 12-11=10, LOW: 15-14=00, 12=0
                switch (op) {
                  case 0x38:
                  case 0x39:
                    {
                        const IntRegIndex rn =
                            (IntRegIndex)(uint32_t)bits(machInst, 19, 16);
                        const uint8_t byteMask = bits(machInst, 11, 8);
                        const bool    r        = bits(machInst, 20);
                        if (bits(machInst, 5)) {
                            const uint8_t sysM = (bits(machInst, 4) << 4) |
                                                  byteMask;
                            return new MsrBankedReg(machInst, rn, sysM, r);
                        } else {
                            if (r) {
                                return new MsrSpsrReg(machInst, rn, byteMask);
                            } else {
                                return new MsrCpsrReg(machInst, rn, byteMask);
                            }
                        }
                    }
                  case 0x3a:
                    {
                        const uint32_t op1 = bits(machInst, 10, 8);
                        const uint32_t op2 = bits(machInst, 7, 0);
                        if (op1 != 0) {
                            const bool enable = bits(machInst, 10, 9) == 0x2;
                            const uint32_t mods = bits(machInst, 8, 0) |
                                                  ((enable ? 1 : 0) << 9);
                            return new Cps(machInst, mods);
                        } else if ((op2 & 0xf0) == 0xf0) {
                            return new Dbg(machInst);
                        } else {
                            switch (op2) {
                              case 0x0:
                                return new NopInst(machInst);
                              case 0x1:
                                return new YieldInst(machInst);
                              case 0x2:
                                return new WfeInst(machInst);
                              case 0x3:
                                return new WfiInst(machInst);
                              case 0x4:
                                return new SevInst(machInst);
                              default:
                                break;
                            }
                        }
                        break;
                    }
                  case 0x3b:
                    {
                        const uint32_t op = bits(machInst, 7, 4);
                        switch (op) {
                          case 0x0:
                            return new Leavex(machInst);
                          case 0x1:
                            return new Enterx(machInst);
                          case 0x2:
                            return new Clrex(machInst);
                          case 0x4:
                            return new Dsb(machInst, 0);
                          case 0x5:
                            return new Dmb(machInst, 0);
                          case 0x6:
                            return new Isb(machInst, 0);
                          default:
                            break;
                        }
                        break;
                    }
                  case 0x3c:
                    {
                        return new BxjReg(machInst,
                                 (IntRegIndex)(uint32_t)bits(machInst, 19, 16),
                                 COND_UC);
                    }
                  case 0x3d:
                    {
                        const uint32_t imm32 = bits(machInst, 7, 0);
                        if (imm32 == 0) {
                            return new Eret(machInst);
                        } else {
                            return new SubsImmPclr(machInst, INTREG_PC,
                                                   INTREG_LR, imm32, false);
                        }
                    }
                  case 0x3e:
                  case 0x3f:
                    {

                        const IntRegIndex rd =
                            (IntRegIndex)(uint32_t)bits(machInst, 11, 8);
                        const bool    r        = bits(machInst, 20);
                        if (bits(machInst, 5)) {
                            const uint8_t sysM = (bits(machInst, 4) << 4) |
                                                  bits(machInst, 11, 8);
                            return new MrsBankedReg(machInst, rd, sysM, r);
                        } else {
                            if (r) {
                                return new MrsSpsr(machInst, rd);
                            } else {
                                return new MrsCpsr(machInst, rd);
                            }
                        }
                    }
                  case 0x7e:
                    {
                        uint32_t imm16 = (bits(machInst, 19, 16) << 12) |
                                         (bits(machInst, 11,  0) <<  0);
                        return new Hvc(machInst, imm16);
                    }
                }
                break;
            }
          case 0x1:
            {
                const uint32_t s = bits(machInst, 26);
                const uint32_t i1 = !(bits(machInst, 13) ^ s);
                const uint32_t i2 = !(bits(machInst, 11) ^ s);
                const uint32_t imm10 = bits(machInst, 25, 16);
                const uint32_t imm11 = bits(machInst, 10, 0);
                const int32_t imm = sext<25>((s << 24) |
                                             (i1 << 23) | (i2 << 22) |
                                             (imm10 << 12) | (imm11 << 1));
                return new B(machInst, imm, COND_UC);
            }
          case 0x4:
            {
                if (bits(machInst, 0) == 1) {
                    return new Unknown(machInst);
                }
                const uint32_t s = bits(machInst, 26);
                const uint32_t i1 = !(bits(machInst, 13) ^ s);
                const uint32_t i2 = !(bits(machInst, 11) ^ s);
                const uint32_t imm10h = bits(machInst, 25, 16);
                const uint32_t imm10l = bits(machInst, 10, 1);
                const int32_t imm = sext<25>((s << 24) |
                                             (i1 << 23) | (i2 << 22) |
                                             (imm10h << 12) | (imm10l << 2));
                return new BlxImm(machInst, imm, COND_UC);
            }
          case 0x5:
            {
                const uint32_t s = bits(machInst, 26);
                const uint32_t i1 = !(bits(machInst, 13) ^ s);
                const uint32_t i2 = !(bits(machInst, 11) ^ s);
                const uint32_t imm10 = bits(machInst, 25, 16);
                const uint32_t imm11 = bits(machInst, 10, 0);
                const int32_t imm = sext<25>((s << 24) |
                                             (i1 << 23) | (i2 << 22) |
                                             (imm10 << 12) | (imm11 << 1));
                return new Bl(machInst, imm, COND_UC);
            }
          default:
            break;
        }
        return new Unknown(machInst);
    }
    '''
}};