convert into mips.

if (j < 0x80) { // j fits in 7 bits, expand to 8 bits // n = j } else if (j <= 0x7FF) { // j fits in 11 bits, expand to 16 bits // b = low 6 bits of j // a = next 5 bits of j // n = 110 a 10 b // 5 6 bits in // j = aaaaa bbbbbb // 3 5 2 6 bits out // n = 110 aaaaa 10 bbbbbb } else if (j <= 0xFFFF) { // j fits in 16 bits, expand to 24 bits // c = low 6 bits of j // b = next 6 bits of j // a = next 4 bits of j // n = 1110 a 10 b 10 c // 4 6 6 bits in // j = aaaa bbbbbb cccccc // 4 4 2 6 2 6 bits out // n = 1110 aaaa 10 bbbbbb 10 cccccc } else if (j <= 0x10FFFF) { // j fits in 21 bits, expand to 32 bits // d = low 6 bits of j // c = next 6 bits of j // b = next 6 bits of j // a = next 3 bits of j // n = 11110 a 10 b 10 c 10 d // 3 6 6 6 bits in // j = aaa bbbbbb cccccc dddddd // 5 3 2 6 2 6 2 6 bits out // n = 11110 aaa 10 bbbbbb 10 cccccc 10 dddddd } else { // j is outside the UTF-8 range of character codes // n = 0xFFFFFFFF