OPEN.BIN Build New-File Header for OPENBK Image

p1 = OPENBK.BIN image ID
p2 = file destination

00069cc8: 27bdffe0 addiu r29,r29,0xffe0
00069ccc: 3c028008 lui r2,0x8008
00069cd0: 8c425ca8 lw r2,0x5ca8(r2)
00069cd4: 00a03821 addu r7,r5,r0                     dest. ptr
00069cd8: 10820013 beq r4,r2,0x00069d28              skip if OPENBK file is already opened
00069cdc: afbf0018 sw r31,0x0018(r29)
00069ce0: 3c050001 lui r5,0x0001
00069ce4: 34a55243 ori r5,r5,0x5243                  OPENBK.BIN
00069ce8: 00041080 sll r2,r4,0x02
00069cec: 3c018008 lui r1,0x8008
00069cf0: ac245ca8 sw r4,0x5ca8(r1)                  store current OPENBK file opened
00069cf4: 3c048005 lui r4,0x8005
00069cf8: 2484eaf4 addiu r4,r4,0xeaf4                file header information
00069cfc: 3c018007 lui r1,0x8007
00069d00: 24213f58 addiu r1,r1,0x3f58
00069d04: 00220821 addu r1,r1,r2
00069d08: 8c230000 lw r3,0x0000(r1)                  offset of OPENBK file to open from file
00069d0c: 3c018007 lui r1,0x8007
00069d10: 24213f5c addiu r1,r1,0x3f5c              
00069d14: 00220821 addu r1,r1,r2
00069d18: 8c260000 lw r6,0x0000(r1)                  filesize of OPENBK Image (+ extra? is this value cumulative?)
00069d1c: 00652821 addu r5,r3,r5                     LBA of image to open
00069d20: 0c01a675 jal 0x000699d4                    OPEN.BIN Build New File-to-open header 
00069d24: 00c33023 subu r6,r6,r3                     filesize - offset
00069d28: 8fbf0018 lw r31,0x0018(r29)
00069d2c: 27bd0020 addiu r29,r29,0x0020
00069d30: 03e00008 jr r31
00069d34: 00000000 nop