嵌套數組用於循環，MIPS組裝

Question

我獲得了以下C代碼，以在MIPS匯編中實現。

for(i=0; i<16, i++){
  for(i=0; j<16, j++){
    C[i][j] = A[i][j] = B[j][i]
  }
}

數組已經為我們初始化了，我們只需要處理內存即可。

這是我制作嵌套循環的方式。

  First:
    bge $t1, $t0, Exit
        Second:
            bge $t2, $t0, Continue
    #do work here.
            addi $t2, $t2, 1
            j Second
    Continue:
    addi $t1, $t1, 1
    j First
   Exit:

加載計數器：

addi $t0, $t0, 16

move $t1, $zero
move $t2, $zero

la $t3, A
la $t4, B
la $t5, C

以及A [i] [j]的邏輯，使用公式Base + Word Length *（行*最大大小+ Col） ：

    sllv $t6, $t0, $t1 #Row, shift 16 by current counter -> 32 -> 64..
    addu $t6, $t6, $t2 #Column, add column counter.
    sll $t6, $t6, 2 #Shift entire count by word length.
    addu $t6, $t6, $t3 #Add A base address.
    lw $t7, ($t6) #Load word from that address.

完整代碼：

    addi $t0, $t0, 16

    move $t1, $zero
    move $t2, $zero

    la $t3, A
    la $t4, B
    la $t5, C

First:
    bge $t1, $t0, Exit
        Second:
            bge $t2, $t0, Continue

            ###

            #Zero out counters first.
            move $t6, $zero
            move $t7, $zero
            move $t8, $zero
            move $t9, $zero

            sllv $t6, $t0, $t1 #Row, shift 16 by current counter -> 32 -> 64..
            addu $t6, $t6, $t2 #Column, add column counter.
            sll $t6, $t6, 2 #Shift entire count by word length.
            addu $t6, $t6, $t3 #Add A base address.
            lw $t7, ($t6) #Load word from that address.

            sllv $t7, $t0, $t2 #Row, shift 16 by current counter -> 32 -> 64..
            addu $t7, $t7, $t1 #Column, add column counter.
            sll $t7, $t7, 2 #Shift entire count by word length.
            addu $t7, $t7, $t4 #Add B base address.
            lw $t8, ($t7) #Load word from that address.

            addu $t9, $t7, $t8 #add A and B results.

            addu $t7, $t6, $t5 #add C base address, reuses $t7, copies $t6 from *A* array.

            sw $t9, 0($t7)  #store above result to C.

            ###

            addi $t2, $t2, 1
        j Second
    Continue:
    addi $t1, $t1, 1
    j First
Exit:

我收到一個錯誤的地址錯誤，但似乎無法弄清楚什么地方出了錯。

Answer 1

至少存在三個錯誤：

• 您正在覆蓋$t6 ，它應該具有A和C的偏移量以及A的基地址
• 您正在覆蓋$t7 ，該地址應包含地址B [j] [i]中的A [i] [j]
• 您正在錯誤地計算行偏移量。 而不是移動16行時間，您應該將行移動4次（有效地將行乘以16）

你可能會改變

sllv $t6, $t0, $t1 #Row, shift 16 by current counter -> 32 -> 64..
   ...
addu $t6, $t6, $t3 #Add A base address.
lw $t7, ($t6) #Load word from that address.
   ...
sllv $t7, $t0, $t2 #Row, shift 16 by current counter -> 32 -> 64..
   ...
addu $t9, $t7, $t8 #add A and B results

同

sll $t6, $t1, 4   # Row
   ...
addu $t7, $t6, $t3 #Add A base address.
lw $t9, ($t7) #Load word from that address.
   ...
sll $t7, $t2, 4  # Row
   ...
addu $t9, $t9, $t8 #add A and B results.