From 71f74625f47c8ad86a86a2a21a06639c784bd1e3 Mon Sep 17 00:00:00 2001
From: Hannes Karppila <hannes.karppila@gmail.com>
Date: Wed, 31 Jul 2024 18:57:06 +0300
Subject: [PATCH] Add LDC changes

---
 src/fuel-vm/instruction-set.md | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/src/fuel-vm/instruction-set.md b/src/fuel-vm/instruction-set.md
index 8f3368af..61d99be8 100644
--- a/src/fuel-vm/instruction-set.md
+++ b/src/fuel-vm/instruction-set.md
@@ -91,7 +91,7 @@
   - [`CCP`: Code copy](#ccp-code-copy)
   - [`CROO`: Code Merkle root](#croo-code-merkle-root)
   - [`CSIZ`: Code size](#csiz-code-size)
-  - [`LDC`: Load code from an external contract](#ldc-load-code-from-an-external-contract)
+  - [`LDC`: Load code from an external contract](#ldc-load-code-from-an-external-contract-or-blob)
   - [`LOG`: Log event](#log-log-event)
   - [`LOGD`: Log data event](#logd-log-data-event)
   - [`MINT`: Mint new coins](#mint-mint-new-coins)
@@ -1796,27 +1796,37 @@ Panic if:
 - `$rB + 32` overflows or `> VM_MAX_RAM`
 - Contract with ID `MEM[$rB, 32]` is not in `tx.inputs`
 
-### `LDC`: Load code from an external contract
+### `LDC`: Load code from an external contract or blob
 
 |             |                                                                                                                                                   |
 |-------------|---------------------------------------------------------------------------------------------------------------------------------------------------|
-| Description | Copy `$rC` bytes of code starting at `$rB` for contract with ID equal to the 32 bytes in memory starting at `$rA` into memory starting at `$ssp`. |
-| Operation   | ```MEM[$ssp, $rC] = code($rA, $rB, $rC);```                                                                                                       |
-| Syntax      | `ldc $rA, $rB, $rC`                                                                                                                               |
-| Encoding    | `0x00 rA rB rC -`                                                                                                                                 |
+| Description | Copy `$rC` bytes of code at offset `$rB` from object with 32 byte id starting at `$rA` into memory starting at `$ssp`. Object type is in `imm`.   |
+| Operation   | `id = mem[$rA,32]; code = match imm { 0 => contract_code($id), 1 => blob_payload($id) }; MEM[$ssp, $rC] = code[$rB, $rC];`                        |
+| Syntax      | `ldc $rA, $rB, $rC, imm`                                                                                                                          |
+| Encoding    | `0x00 rA rB rC imm`                                                                                                                               |
 | Notes       | If `$rC` is greater than the code size, zero bytes are filled in.                                                                                 |
 
+Object type from `imm` determined the source for loading as follows:
+
+| `imm` | Object type   |
+|-------|---------------|
+| `0`   | Contract code |
+| `1`   | Blob payload  |
+| other | *reserved*    |
+
 Panic if:
 
 - `$ssp + $rC` overflows or `> VM_MAX_RAM`
 - `$rA + 32` overflows or `> VM_MAX_RAM`
 - `$ssp + $rC >= $hp`
-- `$rC > CONTRACT_MAX_SIZE`
-- Contract with ID `MEM[$rA, 32]` is not in `tx.inputs`
+- `imm == 0` and `$rC > CONTRACT_MAX_SIZE`
+- `imm == 0` and contract with ID `MEM[$rA, 32]` is not in `tx.inputs`
+- `imm == 1` and contract with ID `MEM[$rA, 32]` is not found in the chain state
+- `imm >= 2` (reserved value)
 
 Increment `$fp->codesize`, `$ssp` by `$rC` padded to word alignment. Then set `$sp` to `$ssp`.
 
-This instruction can be used to concatenate the code of multiple contracts together. It can only be used when the stack area of the call frame is zero-sized.
+This instruction can be used to concatenate the code of multiple contracts or blobs together. It can only be used when the stack area of the call frame is zero-sized.
 
 ### `LOG`: Log event