Pepelatz MISC
Overview
Pepelatz zero edition is my first project on Verilog.
On this page i shall place my plans about it.
Please, comment it.
Instruction set
Num | Mnemonic | Comment |
00 | add |
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01 | sub |
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02 | and |
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03 | or |
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04 | xor |
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05 | shr |
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06 | shl |
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07 | drop | SP--; |
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08 | inc |
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09 | dec |
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0A | not |
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0B | svap | S0 |
0C | rot | S0 |
0D | store | Save value to memory. *Does not SP--!!! |
0E | setcall | Push value from arithmetic stack to call stack.* |
0F | dropcall | Drops call stack.* |
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10 | const | Loads a constant from ITh. |
11 | load | Loads [S0] from memory.* |
12 | getcall | Gets value from call stack. Does not drop call stack! |
13 | dup | Duplicates S0. |
14 | dupd | Duplicates S1 (to stack top). |
15 | isover | Overflow control. |
16 | isneg | Negate control. |
17 | nop |
|
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18 | loop | Starts current command from beginning. |
19 | loop1 | Loads an operand and starts current command from beginning. |
1A | skip | Goes to the next command. |
1B | call | Push PC into call stack and go to address |
1C | if | if S0=0 then jmp |
1D | jump | PC=S0 |
1E | loopz | If C[0]!=0, dec C[0] and starts current command from beginning. |
1F | ifloop | If C[0]!=0, dec C[0] and jmp. |
Warring I. PC is a pointer to the next command, not instruction. Jump and call is not jumping. Jumping will happen after the end of current instruction or after skip command.
Warring II. After changing PC, operands will be read from the new address!
Note I. After changing PC, ITh will be overwritten.