// Emit the AC components.
	h, runLength := huffIndex(2*q+1), int32(0)
	for zig := 1; zig < blockSize; zig++ {
		ac := div(b[unzig[zig]], 8*int32(e.quant[q][zig]))
		if ac == 0 {
			runLength++
		} else {
			for runLength > 15 {
				e.emitHuff(h, 0xf0)
				runLength -= 16
			}
			e.emitHuffRLE(h, runLength, ac)
			runLength = 0
		}
	}
	if runLength > 0 {
		e.emitHuff(h, 0x00)
	}

// This represents n matches with len(x)/n submatches each.
func build(n int, x ...int) [][]int {
	ret := make([][]int, n)
	runLength := len(x) / n
	j := 0
	for i := range ret {
		ret[i] = make([]int, runLength)
		copy(ret[i], x[j:])
		j += runLength
		if j > len(x) {
			panic("invalid build entry")
		}
	}
	return ret
}

// First the simple cases.

        if (runStart < 0) {
          runStart = i;
        }
      } else if (runStart >= 0) {
        int runLength = i - runStart;
        if (runLength > bestRunLength) {
          bestRunStart = runStart;
          bestRunLength = runLength;
        }
        runStart = -1;
      }
    }
    if (bestRunLength >= 2) {

        if (runStart < 0) {
          runStart = i;
        }
      } else if (runStart >= 0) {
        int runLength = i - runStart;
        if (runLength > bestRunLength) {
          bestRunStart = runStart;
          bestRunLength = runLength;
        }
        runStart = -1;
      }
    }
    if (bestRunLength >= 2) {