From 290bed78c02faa9ce59a9812424e968070bd32f8 Mon Sep 17 00:00:00 2001
From: John Adler <john.adler@protonmail.ch>
Date: Thu, 9 Jun 2022 16:46:52 -0400
Subject: [PATCH] Add gas price factor.

---
 specs/protocol/tx_format.md   | 25 +++++++++++++------------
 specs/protocol/tx_validity.md |  8 ++++----
 2 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/specs/protocol/tx_format.md b/specs/protocol/tx_format.md
index 23e716fb..3c48e025 100644
--- a/specs/protocol/tx_format.md
+++ b/specs/protocol/tx_format.md
@@ -22,18 +22,19 @@
 
 ## Constants
 
-| name                        | type     | value | description                                   |
-|-----------------------------|----------|-------|-----------------------------------------------|
-| `GAS_PER_BYTE`              | `uint64` |       | Gas charged per byte of the transaction.      |
-| `MAX_GAS_PER_TX`            | `uint64` |       | Maximum gas per transaction.                  |
-| `MAX_INPUTS`                | `uint64` | `8`   | Maximum number of inputs.                     |
-| `MAX_OUTPUTS`               | `uint64` | `8`   | Maximum number of outputs.                    |
-| `MAX_PREDICATE_LENGTH`      | `uint64` |       | Maximum length of predicate, in instructions. |
-| `MAX_PREDICATE_DATA_LENGTH` | `uint64` |       | Maximum length of predicate data, in bytes.   |
-| `MAX_SCRIPT_LENGTH`         | `uint64` |       | Maximum length of script, in instructions.    |
-| `MAX_SCRIPT_DATA_LENGTH`    | `uint64` |       | Maximum length of script data, in bytes.      |
-| `MAX_STORAGE_SLOTS`         | `uint16` | `255` | Maximum number of initial storage slots.      |
-| `MAX_WITNESSES`             | `uint64` | `16`  | Maximum number of witnesses.                  |
+| name                        | type     | value           | description                                   |
+|-----------------------------|----------|-----------------|-----------------------------------------------|
+| `GAS_PER_BYTE`              | `uint64` |                 | Gas charged per byte of the transaction.      |
+| `GAS_PRICE_FACTOR`          | `uint64` | `1,000,000,000` | Unit factor for gas price.                    |
+| `MAX_GAS_PER_TX`            | `uint64` |                 | Maximum gas per transaction.                  |
+| `MAX_INPUTS`                | `uint64` | `8`             | Maximum number of inputs.                     |
+| `MAX_OUTPUTS`               | `uint64` | `8`             | Maximum number of outputs.                    |
+| `MAX_PREDICATE_LENGTH`      | `uint64` |                 | Maximum length of predicate, in instructions. |
+| `MAX_PREDICATE_DATA_LENGTH` | `uint64` |                 | Maximum length of predicate data, in bytes.   |
+| `MAX_SCRIPT_LENGTH`         | `uint64` |                 | Maximum length of script, in instructions.    |
+| `MAX_SCRIPT_DATA_LENGTH`    | `uint64` |                 | Maximum length of script data, in bytes.      |
+| `MAX_STORAGE_SLOTS`         | `uint16` | `255`           | Maximum number of initial storage slots.      |
+| `MAX_WITNESSES`             | `uint64` | `16`            | Maximum number of witnesses.                  |
 
 ## TransactionType
 
diff --git a/specs/protocol/tx_validity.md b/specs/protocol/tx_validity.md
index 1dd9d0e1..ad1031c4 100644
--- a/specs/protocol/tx_validity.md
+++ b/specs/protocol/tx_validity.md
@@ -100,9 +100,9 @@ def unavailable_balance(tx, col) -> int:
     monotonic and the cost of Ethereum calldata more than makes up for this
     """
     sentBalance = sum_outputs(tx, col)
-    gasBalance = gasPrice * gasLimit
+    gasBalance = ceiling((gasPrice * gasLimit) / GAS_PRICE_FACTOR)
     # Size excludes witness data as it is malleable (even by third parties!)
-    bytesBalance = size(tx) * gasPrice * GAS_PER_BYTE
+    bytesBalance = ceiling((size(tx) * gasPrice * GAS_PER_BYTE) / GAS_PRICE_FACTOR)
     # Only native coin can be used to pay for gas
     if col != 0:
         return sentBalance
@@ -154,7 +154,7 @@ Once the free balances are computed, the [script is executed](../vm/main.md#scri
 1. The unspent free balance `unspentBalance` for each asset ID.
 1. The unspent gas `unspentGas` from the `$ggas` register.
 
-The fees incurred for a transaction are `(tx.gasLimit - unspentGas) * tx.gasPrice`.
+The fees incurred for a transaction are `ceiling(((tx.gasLimit - unspentGas) * tx.gasPrice) / GAS_PRICE_FACTOR)`.
 
 If the transaction as included in a block does not match this final transaction, the block is invalid.
 
@@ -168,7 +168,7 @@ Given transaction `tx`, state `state`, and contract set `contracts`, the followi
 
 If change outputs are present, they must have:
 
-1. if the transaction does not revert; an `amount` of `unspentBalance + unspentGas * tx.gasPrice` if their asset ID is `0`, or an `amount` of the unspent free balance for that asset ID after VM execution is complete, or
+1. if the transaction does not revert; an `amount` of `unspentBalance + floor((unspentGas * tx.gasPrice) / GAS_PRICE_FACTOR)` if their asset ID is `0`, or an `amount` of the unspent free balance for that asset ID after VM execution is complete, or
 1. if the transaction reverts; an `amount` of the initial free balance plus `unspentGas * tx.gasPrice` if their asset ID is `0`, or an `amount` of the initial free balance for that asset ID.
 
 ### State Changes