ref price offset enhance

programs/drift/src/controller/amm.rs

@@ -192,9 +192,20 @@ pub fn update_spreads(
             market.amm.max_base_asset_reserve,
         )?;
 
-        let signed_liquidity_ratio =
+        let mut signed_liquidity_ratio =
             liquidity_ratio.safe_mul(market.amm.get_protocol_owned_position()?.signum().cast()?)?;
 
+        let deadband_pct = market.get_reference_offset_deadband_pct()?;
+        if signed_liquidity_ratio.unsigned_abs() <= deadband_pct {
+            signed_liquidity_ratio = 0;
+        } else {
+            signed_liquidity_ratio = signed_liquidity_ratio.safe_sub(
+                deadband_pct
+                    .cast::<i128>()?
+                    .safe_mul(signed_liquidity_ratio.signum())?,
+            )?;
+        }
+
         amm_spread::calculate_reference_price_offset(
             reserve_price,
             market.amm.last_24h_avg_funding_rate,

programs/drift/src/instructions/admin.rs

@@ -983,7 +983,8 @@ pub fn handle_initialize_perp_market(
         protected_maker_dynamic_divisor: 0,
         padding1: 0,
         last_fill_price: 0,
-        padding: [0; 24],
+        reference_offset_deadband_pct: 0,
+        padding: [0; 23],
         amm: AMM {
             oracle: *ctx.accounts.oracle.key,
             oracle_source,

programs/drift/src/math/amm_spread.rs

@@ -10,10 +10,9 @@ use crate::math::casting::Cast;
 use crate::math::constants::{
     AMM_TIMES_PEG_TO_QUOTE_PRECISION_RATIO_I128, AMM_TO_QUOTE_PRECISION_RATIO_I128,
     BID_ASK_SPREAD_PRECISION, BID_ASK_SPREAD_PRECISION_I128, DEFAULT_LARGE_BID_ASK_FACTOR,
-    DEFAULT_REVENUE_SINCE_LAST_FUNDING_SPREAD_RETREAT, FUNDING_RATE_BUFFER,
-    MAX_BID_ASK_INVENTORY_SKEW_FACTOR, PEG_PRECISION, PERCENTAGE_PRECISION,
-    PERCENTAGE_PRECISION_I128, PERCENTAGE_PRECISION_U64, PRICE_PRECISION, PRICE_PRECISION_I128,
-    PRICE_PRECISION_I64,
+    DEFAULT_REVENUE_SINCE_LAST_FUNDING_SPREAD_RETREAT, MAX_BID_ASK_INVENTORY_SKEW_FACTOR,
+    PEG_PRECISION, PERCENTAGE_PRECISION, PERCENTAGE_PRECISION_I128, PERCENTAGE_PRECISION_I64,
+    PERCENTAGE_PRECISION_U64, PRICE_PRECISION, PRICE_PRECISION_I128, PRICE_PRECISION_I64,
 };
 use crate::math::safe_math::SafeMath;
 use crate::state::perp_market::{ContractType, PerpMarket, AMM};
@@ -193,6 +192,37 @@ pub fn calculate_inventory_liquidity_ratio(
     Ok(amm_inventory_pct)
 }
 
+pub fn calculate_inventory_liquidity_ratio_for_reference_price_offset(
+    base_asset_amount_with_amm: i128,
+    base_asset_reserve: u128,
+    min_base_asset_reserve: u128,
+    max_base_asset_reserve: u128,
+) -> DriftResult<i128> {
+    // computes min(1, x/(1-x)) for 0 < x < 1
+
+    // inventory scale
+    let (max_bids, max_asks) = _calculate_market_open_bids_asks(
+        base_asset_reserve,
+        min_base_asset_reserve,
+        max_base_asset_reserve,
+    )?;
+
+    let avg_liquidity = (max_bids.safe_add(max_asks.abs())?).safe_div(2)?;
+
+    let amm_inventory_pct = if base_asset_amount_with_amm.abs() < avg_liquidity {
+        base_asset_amount_with_amm
+            .abs()
+            .safe_mul(PERCENTAGE_PRECISION_I128)
+            .unwrap_or(i128::MAX)
+            .safe_div(avg_liquidity.max(1))?
+            .min(PERCENTAGE_PRECISION_I128)
+    } else {
+        PERCENTAGE_PRECISION_I128 // 100%
+    };
+
+    Ok(amm_inventory_pct)
+}
+
 pub fn calculate_spread_inventory_scale(
     base_asset_amount_with_amm: i128,
     base_asset_reserve: u128,
@@ -587,17 +617,12 @@ pub fn calculate_reference_price_offset(
         .cast::<i64>()?
         .safe_sub(oracle_twap_slow)?
         .clamp(-max_offset_in_price, max_offset_in_price);
-    // convert last_24h_avg_funding_rate to quote denominated premium
-    let mark_premium_day: i64 = last_24h_avg_funding_rate
-        .safe_div(FUNDING_RATE_BUFFER.cast()?)?
-        .safe_mul(24)?
-        .clamp(-max_offset_in_price, max_offset_in_price); // todo: look at how 24h funding is calc w.r.t. the funding_period
 
     // take average clamped premium as the price-based offset
     let mark_premium_avg = mark_premium_minute
-        .safe_add(mark_premium_hour)?
-        .safe_add(mark_premium_day)?
-        .safe_div(3_i64)?;
+        .safe_mul(75)?
+        .safe_add(mark_premium_hour.safe_mul(25)?)?
+        .safe_div(100_i64)?;
 
     let mark_premium_avg_pct: i64 = mark_premium_avg
         .safe_mul(PRICE_PRECISION_I64)?
@@ -613,7 +638,9 @@ pub fn calculate_reference_price_offset(
     let offset_pct = if (mark_premium_avg_pct >= 0 && inventory_pct >= 0)
         || (mark_premium_avg_pct <= 0 && inventory_pct <= 0)
     {
-        mark_premium_avg_pct.safe_add(inventory_pct)?
+        mark_premium_avg_pct
+            .safe_mul(inventory_pct.cast::<i64>()?)?
+            .safe_div(PERCENTAGE_PRECISION_I64)?
     } else {
         0
     };

programs/drift/src/state/perp_market.rs

@@ -236,7 +236,10 @@ pub struct PerpMarket {
     pub protected_maker_dynamic_divisor: u8,
     pub padding1: u32,
     pub last_fill_price: u64,
-    pub padding: [u8; 24],
+    /// Reference price offset deadband percentage (0-100). 0 disables deadband.
+    /// Stored in former padding to preserve zero-copy layout.
+    pub reference_offset_deadband_pct: u8,
+    pub padding: [u8; 23],
 }
 
 impl Default for PerpMarket {
@@ -280,7 +283,8 @@ impl Default for PerpMarket {
             protected_maker_dynamic_divisor: 0,
             padding1: 0,
             last_fill_price: 0,
-            padding: [0; 24],
+            reference_offset_deadband_pct: 0,
+            padding: [0; 23],
         }
     }
 }
@@ -294,6 +298,10 @@ impl MarketIndexOffset for PerpMarket {
 }
 
 impl PerpMarket {
+    pub fn get_reference_offset_deadband_pct(&self) -> DriftResult<u128> {
+        let pct = self.reference_offset_deadband_pct as u128;
+        Ok(PERCENTAGE_PRECISION.safe_mul(pct)?.safe_div(100_u128)?)
+    }
     pub fn oracle_id(&self) -> OracleIdentifier {
         (self.amm.oracle, self.amm.oracle_source)
     }