branch.isa revision 6253:988a001820f8 
1// -*- mode:c++ -*-
2
3// Copyright (c) 2007-2008 The Florida State University
4// All rights reserved.
5//
6// Redistribution and use in source and binary forms, with or without
7// modification, are permitted provided that the following conditions are
8// met: redistributions of source code must retain the above copyright
9// notice, this list of conditions and the following disclaimer;
10// redistributions in binary form must reproduce the above copyright
11// notice, this list of conditions and the following disclaimer in the
12// documentation and/or other materials provided with the distribution;
13// neither the name of the copyright holders nor the names of its
14// contributors may be used to endorse or promote products derived from
15// this software without specific prior written permission.
16//
17// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
18// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
20// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
21// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
22// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
23// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28//
29// Authors: Stephen Hines
30
31////////////////////////////////////////////////////////////////////
32//
33// Control transfer instructions
34//
35
36def format Branch(code,*opt_flags) {{
37
38    #Build Instruction Flags
39    #Use Link & Likely Flags to Add Link/Condition Code
40    inst_flags = ('IsDirectControl', )
41    for x in opt_flags:
42        if x == 'Link':
43            code += 'LR = NPC;\n'
44        else:
45            inst_flags += (x, )
46
47    #Take into account uncond. branch instruction
48    if 'cond == 1' in code:
49         inst_flags += ('IsUnCondControl', )
50    else:
51         inst_flags += ('IsCondControl', )
52
53    icode =  'if (testPredicate(Cpsr, condCode)) {\n'
54    icode += code
55    icode += '  NPC = NPC + 4 + disp;\n'
56    icode += '} else {\n'
57    icode += '  NPC = NPC;\n'
58    icode += '};\n'
59
60    code = icode
61
62    iop = InstObjParams(name, Name, 'Branch', code, inst_flags)
63    header_output = BasicDeclare.subst(iop)
64    decoder_output = BasicConstructor.subst(iop)
65    decode_block = BasicDecode.subst(iop)
66    exec_output = BasicExecute.subst(iop)
67}};
68
69def format BranchExchange(code,*opt_flags) {{
70    #Build Instruction Flags
71    #Use Link & Likely Flags to Add Link/Condition Code
72    inst_flags = ('IsIndirectControl', )
73    for x in opt_flags:
74        if x == 'Link':
75            code += 'LR = NPC;\n'
76        else:
77            inst_flags += (x, )
78
79    #Take into account uncond. branch instruction
80    if 'cond == 1' in code:
81         inst_flags += ('IsUnCondControl', )
82    else:
83         inst_flags += ('IsCondControl', )
84
85    #Condition code
86
87    icode =  'if (testPredicate(Cpsr, condCode)) {\n'
88    icode += code
89    icode += '  NPC = Rm & 0xfffffffe; // Masks off bottom bit\n'
90    icode += '} else {\n'
91    icode += '  NPC = NPC;\n'
92    icode += '};\n'
93
94    code = icode
95
96    iop = InstObjParams(name, Name, 'BranchExchange', code, inst_flags)
97    header_output = BasicDeclare.subst(iop)
98    decoder_output = BasicConstructor.subst(iop)
99    decode_block = BasicDecode.subst(iop)
100    exec_output = BasicExecute.subst(iop)
101}};
102
103def format Jump(code, *opt_flags) {{
104    #Build Instruction Flags
105    #Use Link Flag to Add Link Code
106    inst_flags = ('IsIndirectControl', 'IsUncondControl')
107    for x in opt_flags:
108        if x == 'Link':
109            code = 'LR = NPC;\n' + code
110        elif x == 'ClearHazards':
111            code += '/* Code Needed to Clear Execute & Inst Hazards */\n'
112        else:
113            inst_flags += (x, )
114
115    iop = InstObjParams(name, Name, 'Jump', code, inst_flags)
116    header_output = BasicDeclare.subst(iop)
117    decoder_output = BasicConstructor.subst(iop)
118    decode_block = BasicDecode.subst(iop)
119    exec_output = BasicExecute.subst(iop)
120    #exec_output = PredOpExecute.subst(iop)
121}};
122
123
124