[SOLVED] How do Int64's work on 32-bit architectures?

[Gizmo]

When using 32-bit Lazarus and FPC on a 32-bit computer, when you declare an Int64, how is it able to use it? And how is the subsequent 32-bit program able to compute those Int64 integers on the 32-bit computers?

I only ask because I use Int64 a lot, to hold large byte count values and the like. They always work fine on 32-bit systems, and its only just occured to me to ask how?

[derek.john.evans]

Same way it has alway been done. Using multiple 32bit calculations.

The 64bit FPC would use the available 64bit processor commands.

[BeniBela]

slowly...

[v.denis]

For example when doing addition on 32-bit machine, first add lower parts (and keep overflow bit), then add higher parts (using overflow bit).

Check these:
http://stackoverflow.com/questions/1652654/adding-64-bit-numbers-using-32-bit-arithmetic
http://stackoverflow.com/questions/23038451/how-does-a-32-bit-processor-support-64-bit-integers