TEA Pseudocode

Encryption:
Input: v0, v1 (64-bit plaintext block as two 32-bit integers)
       k[0], k[1], k[2], k[3] (128-bit key as four 32-bit integers)
       
delta = 0x9E3779B9 (constant based on golden ratio)
sum = 0

for i = 1 to 32 do
    sum = sum + delta
    v0 = v0 + (((v1 << 4) + k[0]) ^ (v1 + sum) ^ ((v1 >> 5) + k[1]))
    v1 = v1 + (((v0 << 4) + k[2]) ^ (v0 + sum) ^ ((v0 >> 5) + k[3]))
end for

Output: v0, v1 (64-bit ciphertext block as two 32-bit integers)

Decryption:
Input: v0, v1 (64-bit ciphertext block as two 32-bit integers)
       k[0], k[1], k[2], k[3] (128-bit key as four 32-bit integers)
       
delta = 0x9E3779B9
sum = delta * 32

for i = 1 to 32 do
    v1 = v1 - (((v0 << 4) + k[2]) ^ (v0 + sum) ^ ((v0 >> 5) + k[3]))
    v0 = v0 - (((v1 << 4) + k[0]) ^ (v1 + sum) ^ ((v1 >> 5) + k[1]))
    sum = sum - delta
end for

Output: v0, v1 (64-bit plaintext block as two 32-bit integers)