From 680a1618d3cf3b2d3dec3090bad559a2c438e57e Mon Sep 17 00:00:00 2001
From: buck54321 <buck54321@gmail.com>
Date: Tue, 2 Feb 2021 14:58:26 -0600
Subject: [PATCH] fix math

---
 client/asset/btc/btc.go |  8 ++++----
 client/asset/dcr/dcr.go | 10 ++++++----
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/client/asset/btc/btc.go b/client/asset/btc/btc.go
index fb5de38d71..c431ee2ea7 100644
--- a/client/asset/btc/btc.go
+++ b/client/asset/btc/btc.go
@@ -826,17 +826,17 @@ func (btc *ExchangeWallet) estimateSwap(lots, lotSize, networkFeeRate uint64, ut
 func (btc *ExchangeWallet) PreRedeem(req *asset.PreRedeemForm) (*asset.PreRedeem, error) {
 	feeRate := btc.feeRateWithFallback(btc.redeemConfTarget)
 	// Best is one transaction with req.Lots inputs and 1 output.
-	var best uint64 = dexbtc.MinimumTxOverhead + dexbtc.TxInOverhead + dexbtc.TxOutOverhead
+	var best uint64 = dexbtc.MinimumTxOverhead
 	// Worst is req.Lots transactions, each with one input and one output.
-	var worst uint64 = best * req.Lots
+	var worst uint64 = dexbtc.MinimumTxOverhead * req.Lots
 	var inputSize, outputSize uint64
 	if btc.segwit {
 		// Add the marker and flag weight here.
-		inputSize = (dexbtc.RedeemSwapSigScriptSize + 2 + 3) / 4
+		inputSize = dexbtc.TxInOverhead + (dexbtc.RedeemSwapSigScriptSize+2+3)/4
 		outputSize = dexbtc.P2WPKHOutputSize
 
 	} else {
-		inputSize = dexbtc.RedeemSwapSigScriptSize
+		inputSize = dexbtc.TxInOverhead + dexbtc.RedeemSwapSigScriptSize
 		outputSize = dexbtc.P2PKHOutputSize
 	}
 	best += inputSize*req.Lots + outputSize
diff --git a/client/asset/dcr/dcr.go b/client/asset/dcr/dcr.go
index 20c0d86111..bc68154235 100644
--- a/client/asset/dcr/dcr.go
+++ b/client/asset/dcr/dcr.go
@@ -810,11 +810,13 @@ func (dcr *ExchangeWallet) PreSwap(req *asset.PreSwapForm) (*asset.PreSwap, erro
 func (dcr *ExchangeWallet) PreRedeem(req *asset.PreRedeemForm) (*asset.PreRedeem, error) {
 	feeRate := dcr.feeRateWithFallback(dcr.redeemConfTarget)
 	// Best is one transaction with req.Lots inputs and 1 output.
-	var best uint64 = dexdcr.MsgTxOverhead + dexdcr.TxInOverhead + dexdcr.TxOutOverhead
+	var best uint64 = dexdcr.MsgTxOverhead
 	// Worst is req.Lots transactions, each with one input and one output.
-	var worst uint64 = best * req.Lots
-	best += dexdcr.RedeemSwapSigScriptSize*req.Lots + dexdcr.P2PKHOutputSize
-	worst += (dexdcr.RedeemSwapSigScriptSize + dexdcr.P2PKHOutputSize) * req.Lots
+	var worst uint64 = dexdcr.MsgTxOverhead * req.Lots
+	var inputSize uint64 = dexdcr.TxInOverhead + dexdcr.RedeemSwapSigScriptSize
+	var outputSize uint64 = dexdcr.P2PKHOutputSize
+	best += inputSize*req.Lots + outputSize
+	worst += (inputSize + outputSize) * req.Lots
 
 	return &asset.PreRedeem{
 		Estimate: &asset.RedeemEstimate{