It is very similar I agree.....but his solution has a problem with the issue that if the upper 4 bits of P0 are set to 1's. My ANL with #07H solves this problem.

You are correct that thesolution does not work correctly. It needs to be modified as follows:

lookup:
db 01h, 02h, 04h, 08h, 10h, 20h, 40h, 80h

mov dptr,#lookup
mov a,P0
anl a,#7H
movc a,@a+dptr
jb P0.3,setp2
mov P1,a
mov P2,#0
sjmp done
setp2:
mov P1,#0
mov P2,a
done:


The modified solution now encodes as follows:

P0.3->P0.0   P2.7->P2.0   P1.7->P1.0
  0 0 0 0     00000000     00000001
  0 0 0 1     00000000     00000010
  0 0 1 0     00000000     00000100
  0 0 1 1     00000000     00001000
  0 1 0 0     00000000     00010000
  0 1 0 1     00000000     00100000
  0 1 1 0     00000000     01000000
  1 1 1 1     00000000     10000000
  1 0 0 0     00000001     00000000
  1 0 0 1     00000010     00000000
  1 0 1 0     00000100     00000000
  1 0 1 1     00001000     00000000
  1 1 0 0     00010000     00000000
  1 1 0 1     00100000     00000000
  1 1 1 0     01000000     00000000
  1 1 1 1     10000000     00000000