everscript

Compiler for assembler based scripts, used in the SNES game "Secret of Evermore".

Almost completely based on the results of SoETilesViewer and the work of Black Sliver.

Currently being developed:

• in/practice.evs (host: romhacking.net)
• in/souls.evs

Idea

The game already uses a script language (instead of pure ASM) for the game logic/story, which can be made available to developers:

• Painless changes on a script level
  • Functions/Macros to reuse code
• Dynamic memory management
  • Scripts and Strings will be allocated automatically
  • if, while, etc. as jump replacement
• IPS format for outputs

Example

Making a gourd teleport the player to the next room: (before and after)

[0x38] Prehistoria - South jungle / Start at 0x9ffec7
  data at 0x9e8000
  enter script at 0x928133 => 0x9384d9
  ...
  B trigger scripts at 0x9e801d, len=0x00ba (31 entries)
    ...
    [38,4a:3a,4c] = (id:7e9 => (802b@928a7d) => addr:0x93802b)
      [0x93802b] (08) IF !($2268&0x40) NOT(Gourd in south Jungle) SKIP 19 (to 0x938044)
      [0x938031] (18) WRITE PRIZE    ($2391) = Petal (0x0800)
      [0x938037] (17) WRITE MAP REF? ($2395) = 0x0000
      [0x93803c] (a3) CALL "Loot gourd?" (0x3a)
      [0x93803e] (0c) $2268 |= 0x40 if ($22ea & 0x01) else $2268 &= ~0x40 (Gourd in south Jungle)
      [0x938044] (00) END (return)

[0x38] Prehistoria - South jungle / Start at 0x9ffec7
  data at 0x9e8000
  enter script at 0x928133 => 0x9384d9
  ...
  B trigger scripts at 0x9e801d, len=0x00ba (31 entries)
    ...
    [38,4a:3a,4c] = (id:7e9 => (802b@928a7d) => addr:0x93802b)
      [0x93802b] (29) CALL 0xb08000 Unnamed ABS script 0xb08000
      [0x93802f] (00) END (return)
    ...
Known abs scripts
    ...
    "Unnamed ABS script 0xb08000" = (addr:0xb08000)
      [0xb08000] (a3) CALL "Fade-out / stop music" (0x00)
      [0xb08002] (0c) $22eb |= 0x20 (in animation)
      [0xb08006] (18) WRITE $238f = 0x0003
      [0xb0800a] (27) Fade-out screen (WRITE $0b83=0x8000)
      [0xb0800b] (a3) CALL "Prepare room change? North exit/south entrance outdoor-indoor?" (0x26)
      [0xb0800d] (a7) SLEEP 15 TICKS
      [0xb0800f] (22) CHANGE MAP = 0x5c @ [ 0x00e8 | 0x0198 ]: "Prehistoria - Raptors"
      [0xb08014] (00) END (return)

IN

everscript --rom "Secret of Evermore (U) [!].smc" --patches "/patches" "in/hello_world.evs"

#memory(
    string_key(0x0000)..string_key(0x232b), // all string keys

    0x300000..0x3fffff // extension
)
#include("in/core.evs")

@install()
@inject(ADDRESS.SOUTH_JUNGLE_ENTER_GOURD_1)
fun enter_map_raptors() {
    transition(MAP.RAPTORS, 0x1d, 0x33, DIRECTION.NORTH, DIRECTION.NORTH);
}

OUT

/out/Secret of Evermore (U) [!].patched.smc

PATCH

13802B 0005      // address=1277995 count=5 name=Token('FUN_IDENTIFIER', 'enter_map_raptors')
29 00 00 0F      // call(11567104)
00               // (00) END (return)"

308000 0015      // address=3178496 count=21 name=Token('FUN_IDENTIFIER', 'enter_map_raptors')
A3 00            // (a3) CALL Fade-out / stop music (0x00)
0c 9d 04 b1      // (0c) $22eb |= 0x20 (in animation)
18 37 01 b3      // (18) WRITE $238f = 0x0003
27               // (27) Fade-out screen (WRITE $0b83=0x8000)
A3 26            // (a3) CALL Prepare room change? North exit/south entrance outdoor-indoor? (0x26)
a7 10            // (a7) SLEEP 15 TICKS
22 1D 33 5C 00   // (22) CHANGE MAP = 0x34 @ [ 0x0090 | 0x0118 ]: ...
00               // (00) END (return)"
EOF

Known Bugs

Everscript

• in/practice.evs
  • NPCs are trashing some dialoges to make space for the new strings and B-triggers

Credits

• SoETilesViewer - Black Sliver
• rply
• ips_util
• /patches/skip_intro.txt - Black Sliver
• /patches/assassin_*.ips - Assassin17
• /patches/debug_menu*.asm - XaserLE
• /research/maps/* - Grizzly