_EFFICIENT MC68HC08 PROGRAMMING_
by Rand Gray and Deepak Mulchandani

Example 1: 

1  main()
2  {
3     int x;
4     int y;
5     int z;
6    
7     y = 7;
8     x = 2*y+1;
9     z = 2*y+1;
10
11  }


Example 2: 

Byte Cycle Instructions

3     4    mov #7, y+1
2     3    clr y
3     4    mov #15, x+1
2     3    clr x
3     4    mov #15, z+1
2     3    clr z



Example 3: 

Byte  Cycle   Compiler-generated output

3     4       mov #7, y+1
2     3       clr y
2     3       ldx y
2     3       lda y+1
1     1       lsla    
1     1       rolx 
2     2       add #1
2     3       sta x+1
1     1       txa     
2     2       adc #0
2     3       sta x
2     3       ldx y
2     3       lda y+1
1     1       lsla    
1     1       rolx    
2     2       add #1
2     3       sta z+1
1     1       txa     
2     2       adc #0
2     3       sta z
1     1       rts 


Example 4: 

1  main()
2  {
3     int x = 6;
4     int y;
5     
6     if (x == 7)
7     {
8        y = 2*3+1;
9        x = 2*y+1
10    }
11    y = x;
12
13 }


Example 5: 

Bytes  Cycle(s)  Compiler-generated output

3      4         mov #6, x+1
2      3         clr x
2      3         lda x+1
2      2         eor #7
2      3         bne L0005
2      3         lda x
2      3         bne L0005
3      4         mov #7, y+1
2      3         clr y
2      3         ldx y
2      3         lda y+1
1      1         lsla    
1      1         rolx    
2      2         add #1
2      3         sta x+1
1      1         txa     
2      2         adc #0
2      3         sta x
            L0005:
3      5         mov x, y
3      5         mov x+1,y+1
1      1         rts