pumpfun-mechanics

k = virtualSolReserves × virtualTokenReserves

price_sol_per_token = virtual_sol_reserves / virtual_token_reserves

# In human-readable units:
price = (virtual_sol / 1e9) / (virtual_token / 1e6)

# At genesis: 30 / 1,073,000,000 ≈ 2.796e-8 SOL/token
# At graduation: ~4.1e-7 SOL/token (~14.7x from launch)

def buy_tokens(v_sol: int, v_tok: int, real_tok: int, sol_in: int) -> int:
    """Calculate tokens received for a given SOL input.

    Args:
        v_sol: Virtual SOL reserves (lamports).
        v_tok: Virtual token reserves (raw).
        real_tok: Real token reserves (raw).
        sol_in: SOL to spend (lamports, BEFORE 1% fee).

    Returns:
        Tokens received (raw units).
    """
    k = v_sol * v_tok
    new_v_sol = v_sol + sol_in
    new_v_tok = k // new_v_sol + 1  # +1 matches on-chain rounding
    tokens_out = v_tok - new_v_tok
    return min(tokens_out, real_tok)

def sell_tokens(v_sol: int, v_tok: int, real_sol: int, tokens_in: int) -> int:
    """Calculate SOL received for selling tokens.

    Args:
        v_sol: Virtual SOL reserves (lamports).
        v_tok: Virtual token reserves (raw).
        real_sol: Real SOL reserves (lamports).
        tokens_in: Tokens to sell (raw units).

    Returns:
        SOL received (lamports, BEFORE 1% fee).
    """
    k = v_sol * v_tok
    new_v_tok = v_tok + tokens_in
    new_v_sol = k // new_v_tok
    sol_out = v_sol - new_v_sol - 1  # -1 matches on-chain floor rounding
    return min(sol_out, real_sol)

def buy_cost(v_sol: int, v_tok: int, tokens_wanted: int) -> int:
    """Calculate SOL needed to buy exact token amount.

    Returns:
        SOL cost in lamports (before fee). Returns max int if impossible.
    """
    if tokens_wanted >= v_tok:
        return 2**64 - 1  # impossible
    k = v_sol * v_tok
    new_v_tok = v_tok - tokens_wanted
    new_v_sol = k // new_v_tok + 1
    return new_v_sol - v_sol

# Buying: fee deducted from SOL input before curve
actual_sol_to_curve = sol_input * 0.99

# Selling: fee deducted from SOL output after curve
actual_sol_received = sol_from_curve * 0.99

# Roundtrip minimum cost: ~2% from fees alone, plus price impact

market_cap_sol = (token_total_supply * virtual_sol_reserves) / virtual_token_reserves

GRADUATION_THRESHOLD = 85_000_000_000  # 85 SOL in lamports

fill_pct = (real_sol_reserves / GRADUATION_THRESHOLD) * 100.0

mint:                  pubkey   32 bytes
solAmount:             u64       8 bytes
tokenAmount:           u64       8 bytes
isBuy:                 bool      1 byte
user:                  pubkey   32 bytes
timestamp:             i64       8 bytes
virtualSolReserves:    u64       8 bytes
virtualTokenReserves:  u64       8 bytes
realSolReserves:       u64       8 bytes
realTokenReserves:     u64       8 bytes

Offset 0:   discriminator          8 bytes
Offset 8:   virtualTokenReserves   u64
Offset 16:  virtualSolReserves     u64
Offset 24:  realTokenReserves      u64
Offset 32:  realSolReserves        u64
Offset 40:  tokenTotalSupply       u64
Offset 48:  complete               bool (1 byte)
Offset 49:  creator                pubkey (32 bytes)

[0..8]:   discriminator
[8..16]:  spendable_sol_in    u64 LE (total SOL budget, fees deducted internally)
[16..24]: min_tokens_out      u64 LE (slippage floor)

[0..8]:   discriminator
[8..16]:  amount_tokens       u64 LE (tokens to sell, raw)
[16..24]: min_sol_output      u64 LE (minimum SOL out, lamports)

def price_impact(v_sol: int, v_tok: int, sol_in: int) -> float:
    """Calculate price impact for a buy as a percentage."""
    spot = v_sol / v_tok
    tokens = buy_tokens(v_sol, v_tok, v_tok, sol_in)
    if tokens == 0:
        return float('inf')
    exec_price = sol_in / tokens
    return (exec_price / spot - 1) * 100

# Example: 1 SOL buy at genesis
# impact = price_impact(30_000_000_000, 1_073_000_000_000_000, 1_000_000_000)
# ≈ 3.3% price impact