Non-Conventional Useof Execution Units

• IS-54 convolutional encoder bit-interleaving on Pentium

  • Pentium can’t do single-cycle

rcl ecx, 1 ; rotate, insert prev carry bit

shl eax, 1 ; shift, generate new carry bit

• But it can do single-cycle

rcl ecx, 1 ; rotate, insert prev carry bit

add eax, eax ; shift, generate new carry bit

• Vector maximum search on the ZSP ZSP164xx

loop: ldu r15,r14,1 ; new 16-bit value in ; r15, address in r14

max.e r4,r14 ; 32-bit max {r5,r4},

;{r15,r14} includes address

agn0 loop ; next value

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