Script for Laboratory: Designing embedded ASIPs - CES

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3.2.2 How to add a new instruction To add a new instruction for a given instruction-format is a doable task. The following list shows you the needed steps. The given line numbers are rounded and might change during time, as the source code is partially under development. Every needed part of the source code is marked with a comment that includes the string “ASIP NEW_INSTRUCTIONS”. 1. dlx.h:235 Add a new define for OP_{CommandName} with a unique number. 2. sim.c:365 Add the name for your assembly-command into the operationNames-array. The position of the name in this array has to correspond with the defined number in dlx.h from the preceding step. 3. asm.c:350 Add a new entry with your instruction name, instruction format and opcode into the opcodes-table. The instruction name should be the same like in the previous step. The already available instruction formats are shown in Figure 3-7. There are two different possibilities for the opcode. Either you use the 6 highest bits or you use the 6 lowest bits for your opcode. The unused bits always stay 0 in the opcode field. These two possibilities differ in how dlxsim is internally handling the instruction. This will become clearer in the following step. You should use the 6 highest bits for the branch instruction formats and the 6 lowest bits for the arithmetic instruction formats. Have a look at the following step to find free opcodes. The following values in the opcode table are usually not that important and might be filled out by copy-and-past from a similar instruction. Only the flags are important if you use instructions with immediate values as parameter. The flags are explained in asm.c. 4. sim.c:335 This step depends on your choice of the preceding step. You have used either the 6 highest bits or the 6 lowest bits for the opcode. If you have used the 6 highest bits, then you have to modify the opTable in sim.c otherwise you have to modify the specialTable. In both cases you replace the table entry at the position that corresponds to the chosen 6-bit opcode with your own OP_{CommandName}. So if you have chosen the opcode value 5, then you replace the 5 th entry (start counting with 0) in the array with your own command. 5. sim.c:1350 Implement a new case for the big “switch (wordPtropcode)”-statement for your command. A good start is a copy-and-paste from a similar instruction. There are 2 different variables for the parameters. For example, there is a “wordPtrrs1” and a “rs1”. In “wordPtrrs1” the number of the first source register is stored, while in “rs1” the value of this source register is stored. At the beginning of an implementation of one specific ‘case’ some macros like “LoadRegisterS1” are called. Those macros take care, that “rs1” is initialized with the current value of the register with the number “wordPtrrs1”. - 24 -
Instruction Format Parameters NO_ARGS no operands LOAD (register, address) STORE (address, register) LUI (dest, 16-bit expression) ARITH_2PARAM (dest, src) OR (dest, 16-bit immediate) OR "dest" replaced by "dest/src1" ARITH_3PARAM (dest, src1, sr2c) OR (dest/src1, src2) OR (dest, src1, 16-bit immediate) OR (dest/src1, 16-bit immediate) ARITH_4PARAM (rd, rs1, rs2, rs3) OR (rd, rs1, rs2, 5-bit immediate) BRANCH_0_OP (label) the source register is implied BRANCH_1_OP (src1, label) BRANCH_2_OP (src1, src2, label) JUMP (label) OR (src1) SRC1 (src1) LABEL (label) MOVE (dest,src1) Figure 3-7 Summary of available dlxsim instruction formats 3.2.3 How to add a new instruction-format Adding a new instruction format is much more difficult than adding a new instruction for a given format. To add a new format you have to take care about how the parameters for your new format are to be stored in a 32-bit instruction word and how they are extracted out of it. Every needed part of the source code is marked with a comment that includes the string “ASIP NEW_FORMAT”. 1. asm.c:140 Define a unique number for your instruction-format 2. asm.c:150 Add the min and max numbers of arguments, that your instruction format accepts in the arrays “minArgs” and “maxArgs”. Use the position in the array, that corresponds to the defined number in the previous step. 3. asm.c:765 Implement how the parameters shall be stored in the 32-bit instruction word within the “switch (insPtr->class)”-statement. 4. asm.c:1080 Implement what shall be written if the instruction is disassembled in the “switch (opPtr->class)”-statement. 5. sim.c:2215 In the method “compile” you have to implement how the 32-bit instruction word shall be expanded. - 25 -
Page 1 and 2: Laboratory: “Designing Applicatio
Page 3 and 4: 6 Validating the CPU in Prototyping
Page 5 and 6: Figure 1-1 GPPs, ASIPs and ASICs [H
Page 7 and 8: • Command line interpreter Intera
Page 9 and 10: i. Copying files: the cp command co
Page 11 and 12: . Copying via ssh: Not all machines
Page 13 and 14: dlx_basis Applications ModelSim mei
Page 15 and 16: makeCoSy contCoSy Filename Explanat
Page 17 and 18: 3 Dlxsim Dlxsim [DLX-Package] is an
Page 19 and 20: Successful Successful dissolving di
Page 21 and 22: Instruction Description Instruction
Page 23: Option Description -dbb# (Debug Bas
Page 27 and 28: Command Description stop {options}
Page 29 and 30: 3.3.2 Debugging with dlxsim This ch
Page 31 and 32: addComment1(); functionY(); addComm
Page 33 and 34: • If you manually want to write a
Page 35 and 36: 4.3 Tutorial for the “Flexible Ha
Page 37 and 38: in direction; The in keyword means
Page 39 and 40: amount : in std_logic_vector(7 down
Page 41 and 42: Add the three signals to the contro
Page 43 and 44: data_in : in std_logic_vector($W1 d
Page 45 and 46: 5 ModelSim ModelSim is a full-featu
Page 47 and 48: 5.1.3 Compile the project Figure 5-
Page 49 and 50: Mark the wave.do file in your Model
Page 51 and 52: Figure 5-6 ModelSim waves Signal Ex
Page 53 and 54: • Always invoke ModelSim in the s
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Page 59 and 60: After the TestData-files for your a
Page 61 and 62: However, you can’t force the synt
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Page 65 and 66: 7 Power estimation In this tutorial
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Page 71 and 72: When you manually have to fix some
Page 73 and 74: of the makeCoSy script. If an error
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the automatically generated compile
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instruction, as different custom in
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Directive Explanation .restrict .ch
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Now we will demonstrate how you can
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the user changes the value of the b
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• Huge decrease of cycle count
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of instructions together it might t
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Table of Figures Figure 1-1 GPPs, A
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References [CES] Homepage of the Ch
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