diff options
| -rw-r--r-- | engines/sci/engine/script_patches.cpp | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/engines/sci/engine/script_patches.cpp b/engines/sci/engine/script_patches.cpp index ac42764e5b..992dd9e8bb 100644 --- a/engines/sci/engine/script_patches.cpp +++ b/engines/sci/engine/script_patches.cpp @@ -30,6 +30,52 @@ namespace Sci { +// IMPORTANT: +// every patch entry needs the following: +// - script number (pretty obvious) +// +// - apply count +// specifies the number of times a patch is supposed to get applied. +// Most of the time, it should be 1. +// +// - magicDWORD + magicOffset +// please ALWAYS put 0 for those two. Both will get filled out at runtime by the patcher. +// +// - signature data (is used to identify certain script code, that needs patching) +// every signature needs to contain SIG_MAGICDWORD once. +// The following 4 bytes after SIG_MAGICDWORD - which don't have to be fixed, you may for example +// use SIG_SELECTOR16, will get used to quickly search for a partly match before verifying that +// the whole signature actually matches. If it's not included, the script patcher will error() out +// right when loading up the game. +// If selector-IDs are included, please use SIG_SELECTOR16 + SIG_SELECTOR8 [1]. Simply +// specify the selector that way, so that the patcher will search for the specific +// selector instead of looking for a hardcoded value. Selectors may not be the same +// between game versions. +// For UINT16s either use SIG_UINT16 or SIG_SELECTOR16. +// Macintosh versions of SCI games are using BE ordering instead of LE since SCI1.1 for UINT16s in scripts +// By using those 2 commands, it's possible to make patches work for PC and Mac versions of the same game. +// You may also skip bytes by using the SIG_ADDTOOFFSET command +// Every signature data needs to get terminated using SIGNATURE_END +// +// - patch data (is used for actually patching scripts) +// When a match is found, the patch data will get applied. +// Patch data is similar to signature data. Just use PATCH_SELECTOR16 + PATCH_SELECTOR8 [1] +// for patching in selectors. +// There are also patch specific commands. +// Those are PATCH_GETORIGINALBYTE, which fetches a byte from the original script +// and PATCH_GETORIGINALBYTEADJUST, which does the same but gets a second value +// from the uint16 array and uses that value to adjust the original byte. +// Every patch data needs to get terminated using PATCH_END +// +// - and please always add a comment about why the patch was done and what's causing issues. +// If possible make sure, that the patch works on localized (or just different) game versions +// as well in case those need patching too. +// +// [1] - selectors need to get specified in selectorTable[] and ScriptPatcherSelectors-enum +// before they can get used using the SIG_SELECTORx and PATCH_SELECTORx commands. +// You have to use the exact same order in both the table and the enum, otherwise +// it won't work. + #define SIG_END 0xFFFF #define SIG_MISMATCH 0xFFFE #define SIG_COMMANDMASK 0xF000 |