SignalChapter 11: Capstones

84FAIR SHARE

The task

X holds frames of up to 6 numbers from 1 to 99, each ended by a 0.

P must receive each frame's sum over its count, and Q the remainder; an empty frame sends 0.

a is an SC-4, with C and D as well. k is an SC-2L: 2 cycles a line, half the energy.

The board

The board as the puzzle screen lays it out. Cyan pins read, lemon pins write, violet pins go both ways. On a narrow screen, scroll the board sideways to see all of it.

Key idea

The sum and the count of a frame meet in one core, which divides for the share and takes MOD for the rest; a divisor of 0 gives 0, so an empty frame needs no test.

Hints

Each hint goes a step further than the one before. Open them one at a time.

Hint 1Show

The sum and the count of a frame are both needed before d can divide.

Hint 2Show

MOV C, A keeps a copy of A in C, and MOV A, C brings it back.

Hint 3Show

A divide leaves A holding the answer, so d may need the sum sent twice.

Solution

Reveal the Full SolutionThe complete program for FAIR SHARE. Open it only when you want the answer.

The reference program

The game's own solution. It passes every test and scores exactly par on every benchmark.

aSC-4 quad

S: IN P0
JNZ K
XCH A, C
OUT P1
MOV A, 0
XCH A, B
OUT P1
OUT P1
JMP S
K: ADD B
MOV B, A
MOV A, C
ADD 1
MOV C, A

dSC-2 standard

IN P0
MOV B, A
IN P0
DIV B
OUT P2
IN P0
MOD B
OUT P3

CYCLES: 353; at par
ENERGY: 3034; at par
NODES: 2; at par
INSTRUCTIONS: 22; at par

Another way: Fair share count on k

A second program that also passes. It beats par on ENERGY and gives some back on CYCLES, NODES, and INSTRUCTIONS.

Less energy than par, but slower and on three nodes. a only sums, and the low power k counts the values a passes on.

aSC-4 quad

S: IN P0
OUT P2
JNZ K
XCH A, B
OUT P1
OUT P1
JMP S
K: ADD B
MOV B, A

kSC-2L low power

S: IN P0
JNZ K
XCH A, B
OUT P1
JMP S
K: XCH A, B
ADD 1
XCH A, B

dSC-2 standard

IN P1
MOV B, A
IN P0
DIV B
OUT P2
IN P0
MOD B
OUT P3

CYCLES: 467; over par
ENERGY: 2922; under par
NODES: 3; over par
INSTRUCTIONS: 25; over par