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| language:langs:prs [2020/04/29 16:56] – created rajit | language:langs:prs [2024/08/07 11:09] (current) – [Loops] rajit | ||
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| The '' | The '' | ||
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| a -> b- | a -> b- | ||
| ~a -> b+ | ~a -> b+ | ||
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| The left-hand side of a production rule is a Boolean expression, and the right hand side specifies the action to be taken when the Boolean expression is true. A more complete example of an inverter in ACT would be: | The left-hand side of a production rule is a Boolean expression, and the right hand side specifies the action to be taken when the Boolean expression is true. A more complete example of an inverter in ACT would be: | ||
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| bool a, b; | bool a, b; | ||
| prs { | prs { | ||
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| A two-input NAND gate with inputs '' | A two-input NAND gate with inputs '' | ||
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| prs { | prs { | ||
| a & b -> c- | a & b -> c- | ||
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| A two-input inverting C-element would be: | A two-input inverting C-element would be: | ||
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| prs { | prs { | ||
| a & b -> c- | a & b -> c- | ||
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| The first common case is a combinational gate like an inverter or NAND. In a combinational gate, the Boolean expression for the pull-up is the complement of the Boolean expression for the pull-down. In this case we can simply specify one, and use the '' | The first common case is a combinational gate like an inverter or NAND. In a combinational gate, the Boolean expression for the pull-up is the complement of the Boolean expression for the pull-down. In this case we can simply specify one, and use the '' | ||
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| prs { | prs { | ||
| a & b => c- | a & b => c- | ||
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| Note that this is the same as specifying | Note that this is the same as specifying | ||
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| prs { | prs { | ||
| ~a | ~b => c+ | ~a | ~b => c+ | ||
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| The second common case is that of C-elements. To specify the two-input C-element above, you can also write | The second common case is that of C-elements. To specify the two-input C-element above, you can also write | ||
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| prs { | prs { | ||
| a & b #> c- | a & b #> c- | ||
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| When defining parameterized circuits, it is helpful to also have the corresponding parametrized production rules that implement the circuit. There are two loop constructs available that use the same " | When defining parameterized circuits, it is helpful to also have the corresponding parametrized production rules that implement the circuit. There are two loop constructs available that use the same " | ||
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| bool x[5], y[5]; | bool x[5], y[5]; | ||
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| The example above creates five inverters when the circuit is expanded. '' | The example above creates five inverters when the circuit is expanded. '' | ||
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| bool x[5], y; | bool x[5], y; | ||
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| The example above is a 5-input NAND gate. Here the replication construct is used with ''&'' | The example above is a 5-input NAND gate. Here the replication construct is used with ''&'' | ||
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| ... | ... | ||
| prs { | prs { | ||
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| Similarly, '' | Similarly, '' | ||
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| prs { | prs { | ||
| en & (|i:5: x[i]) -> y- | en & (|i:5: x[i]) -> y- | ||
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| } | } | ||
| </ | </ | ||
| + | |||
| + | ==== Attributes ==== | ||
| + | |||
| + | Production rules can also be decorated with attributes that are used for a variety of purposes by ACT tools. The meaning of attributes is not pre-defined within the ACT language, but is a convention based on how these attributes are interpreted by various tools. Current attributes and their meanings is available in the section on [[language: | ||
| ==== CMOS implementation ==== | ==== CMOS implementation ==== | ||
| - | The ACT tools provide automated support for converting production rules into a transistor-level implementation. This is done in a way that is entirely under user control, so the way the production rules are written is strictly followed when creating the transistors that implement the production rules. | + | The ACT tools provide automated support for converting production rules into a transistor-level implementation. This is done in a way that is entirely under user control, so the way the production rules are written is strictly followed when creating the transistors that implement the production rules. The tool that performs this conversion is '' |
| === Implementable rules === | === Implementable rules === | ||
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| For a production rule to be // | For a production rule to be // | ||
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| a & b -> c+ | a & b -> c+ | ||
| a & b -> d- | a & b -> d- | ||
| ~a | ~b -> e+ | ~a | ~b -> e+ | ||
| </ | </ | ||
| + | This is because '' | ||
| === Transistor sizing and flavors === | === Transistor sizing and flavors === | ||
| The width, length, flavor, and folding of a transistor can be specified as part of the syntax of production rules. The following examples illustrate the syntax. | The width, length, flavor, and folding of a transistor can be specified as part of the syntax of production rules. The following examples illustrate the syntax. | ||
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| a <10> & b <10> -> c- | a <10> & b <10> -> c- | ||
| </ | </ | ||
| In this example, the widths of the transistor for '' | In this example, the widths of the transistor for '' | ||
| - | < | + | < |
| a < | a < | ||
| </ | </ | ||
| In this example, the transistor specified is one with a width of 20 units and length of 4 units. The default values of width and length for p-type and n-type devices are specified in the [[config: | In this example, the transistor specified is one with a width of 20 units and length of 4 units. The default values of width and length for p-type and n-type devices are specified in the [[config: | ||
| - | < | + | < |
| a < | a < | ||
| </ | </ | ||
| - | Transistors come in different //flavors// in a modern technology. The flavors supported by ACT are specified in the top-level ACT [[config: | + | Transistors come in different //flavors// in a modern technology. The flavors supported by ACT are specified in the top-level ACT [[config: |
| Finally, it is often the case that multiple transistors in an expression use the same sizing information. | Finally, it is often the case that multiple transistors in an expression use the same sizing information. | ||
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| a <10> & b -> c- | a <10> & b -> c- | ||
| </ | </ | ||
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| A rule of the form | A rule of the form | ||
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| a & b -> c- | a & b -> c- | ||
| </ | </ | ||
| Line 158: | Line 163: | ||
| A multi-fingered transistor can be manually specified if necessary. The example | A multi-fingered transistor can be manually specified if necessary. The example | ||
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| (a <10> | a< | (a <10> | a< | ||
| </ | </ | ||
| would have the effect of using two multi-fingered transistors, | would have the effect of using two multi-fingered transistors, | ||
| - | < | + | < |
| a< | a< | ||
| </ | </ | ||
| or, using the implicit sizing rules, as | or, using the implicit sizing rules, as | ||
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| | | ||
| </ | </ | ||
| + | Some additional details of how you can control the circuit being generated from the production rules is described in the [[tools: | ||
| + | === Leakage adjustment === | ||
| + | The leakage adjustment [[config: | ||
| + | <code act> | ||
| + | prs * { | ||
| + | ... | ||
| + | } | ||
| + | </ | ||
| + | The '' | ||
| + | ==== Direct transistor specifications ==== | ||
| + | |||
| + | In case this syntax is not sufficient, the '' | ||
| + | <code act> | ||
| + | prs { | ||
| + | passp < | ||
| + | passn < | ||
| + | } | ||
| + | </ | ||
| + | |||
| + | Note that automatic staticizer (keeper) generation is only triggered when a production rule is specified. If part of your circuit for an output signal is described using production rules and part of it is described using transistors, | ||
| + | |||
| + | ==== Explicit capacitors ==== | ||
| + | |||
| + | The '' | ||
| + | <code act> | ||
| + | prs { | ||
| + | cap (node1, node2); /* explicit capacitor of one unit size between the two nodes */ | ||
| + | cap< | ||
| + | cap< | ||
| + | } | ||
| + | </ | ||
| + | The unit capacitor is specified in the netlist configuration file; if it is unspecified, | ||