Difference between revisions of "Sync"

Latest revision as of 05:39, 31 December 2022

Syntax

Syntax: sync

• None

Use

Sync must be used when creating a thread on a looping function. Examples are functions that wait more than one frame for a condition to occur, such as a room being cleared, a switch being pressed, or a register being set. Sync should be called at least once in such loops. Not using sync inside of these loops may cause the game to freeze.

One sync equals one frame elapsed in game, and 30 frames equals one second. Sega sometimes used multiple syncs in a function to force a specific delay, such as displaying a window_msg some number of frames after zooming in the camera.

On more technical terms, sync will cause the current coroutine to yield, allowing other coroutines to run (thread actually creates a coroutine and not a thread, and they don't run parallelly). Special menus called through opcodes will yield on their own and do not require a sync inside their function.

Opcodes that will automatically yield:

• ret
• exit
• window_msg
• message
• chat_box
• disp_msg_qb
• add_msg
• list
• fadein
• fadeout
• award_item_name
• award_item_select
• award_item_ok
• get_item_id

Example

100:     call 101 //Call function 101
         window_msg 'Okay. I've waited 1 second. Now what?'
         winend 
         ret 
101:     sync //Pause for 1 frame
         addi R1, 00000001 //Add 1 to register R1
         jmpi_<= R1, 0000001E, 101 //If R1 is less then or equal to 30 jump to 101
         clear R1 //Set R1 to 0
         ret 

Also see

ret, call, window_msg, winend, addi, jmp_<=, clear