Multiply:

/*r4 = base exp..*/
/*r5 = foe’s level*/
/*This multiplies the base exp. by the opponent’s level*/
/*Then it multiplies the result by 20*/
/*Then it divides the whole thing by 100*/
/*This is the same as dividing it by 5*/
/*r0 is the top number, r1 is the bottom number*/

mul r4, r5
mov r0, r4 /*r1 is B x L*/
mov r1, #0xFA /*r1 = 250*/
bl Divide /*divides by 250* because dividing by a value over 255 breaks the script. we will divide again by 2 later to simulate division by 500*/
mov r3, r0

LevelStuff:

/*r6 = your level*/
/*r5 = opponent's level*/
/*if r6 is 10+ higher than r5 no exp is earned*/

sub r1, r5, r6  /*(L-Lp)*/
bl Decrypt
ldr r0, =(-10)  /*if player is 10 levels higher */
cmp r1, r0
ble NoExp.      /*then no exp is earned*/
mov r0, #0xA
mul r1, r0      /* 10*(L - Lp) */
mov r2, #0x64
add r1, r1, r2   /* (100 + 10*(L - Lp)) */
mul r1, r3     /* (B * L)/250 * (100 + 10*(L - Lp)) */
mov r0, r1
mov r1, #0x2
bl Divide /*divides by 2 to simulate division by 500*/