classification of isa 比较

6eanut · Sep 28, 2024 · f8e2720 · f8e2720
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commit f8e2720
Showing 1 changed file with 11 additions and 4 deletions.
diff --git a/24-Q4/00_ClassificationofISA.md b/24-Q4/00_ClassificationofISA.md
@@ -59,7 +59,14 @@ D = A - C
 B = D + A
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+注：假设，操作码占用8位，内存地址和操作数都是16位，寄存器型ISA有16个通用寄存器
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+|                              | 堆栈型                                                                                                                           | 累加器型                                                                                                     | 寄存器-存储器型                                                                                            | 寄存器-寄存器型                                                                                                                           |
+| :--------------------------: | -------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
+|      **汇编代码**      | PUSH B<br />PUSH C<br />SUB<br />POP A<br />PUSH A<br />PUSH C<br />SUB<br />POP D<br />PUSH D<br />PUSH A<br />ADD <br />POP B | LOAD C<br />NEG<br />ADD B<br />STORE A<br />LOAD C<br />NEG<br />ADD A<br />STORE D<br />ADD A<br />STORE B | LOAD R1, B<br />SUB R1, C<br />STORE R1, A<br />SUB R1, C<br />STORE R1, D<br />ADD R1, A<br />STORE R1, B | LOAD R1, B<br />LOAD R2, C<br />SUB R3, R1, R2<br />STORE R3, A<br />SUB R4, R3, R2<br />STORE R4, D<br />ADD R5, R4, R3<br />STORE R5, B |
+|       **代码量**       | 12·1+9·2=30                                                                                                                    | 10·1+8·2=**26**                                                                                           | 7·1+7·2+7·1=28                                                                                          | 8·1+5·2+5·1+3·2=29                                                                                                                    |
+| **与内存交换的数据量** | 30+9·2=48                                                                                                                       | 26+8·2=42                                                                                                   | 28+7·2=42                                                                                                 | 29+5·2=**39**                                                                                                                           |
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+结论：在代码量方面，累加器型ISA更优；在与内存交换的数据量方面，寄存器-寄存器型ISA更优
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+补充：因为指令必须是byte的整数倍。所以LOAD R1, B中的R1要占8bit；ADD R5, R4, R3中的R5和R4占8bit，R3占8bit