CallerId_200_final.pbp

; This is a patch to fix iOS CallerID bug
; It works by fixing HandsFreeProtocol initialization procedure
; asking iPhone to send us data in UTF-8 charset
; instead of default 7bit.
#ver 200

; This patch should work with most firmware versions,
; because it only changes Bluetopia library code
; and places its own code instead of unused function
; to the end of firmware binary.

2D E9 FF 4F 85 B0 83 46 15 00 99 46 7E D0 {
	proc HFRE_send
	; args: R0 = stackId,
	;		R1 = [port+8],
	;		R2 = nDataLen,
	;		R3 = pszData
}

; in beginning of HFRE_handle_OK
2D E9 F0 43 04 46 90 F8 23 00 @ 91 B0 80 1E {
	; replacing:
	; SUB SP,SP,0x44
	; SUB R0,R0,2
	B.W my_code
	global continue ; global label
}

; in middle of HFRE_handle_OK
; At last stage of init, it places 0x6 state code. (UPD: actually unused)
; We instead place 64 (0x40) (which is ignored by proc's main code) and handle it ourselves.
;84 F8 44 51 1D E0 @ 06 20 {
;	MOV R0, 64 ; instead of 6
;}
; also 64 instead of 5 - send CSCS instead of CHLD (which actually doesn't get send anyway)
78 B9 @ 05 20 2A E0 94 F8 2C 00 {
	MOV R0, 64 ; instead of 5
}

; in middle of HFRE_handle_OK
; This is its init-handler part
; WARNING: don't currently use it!
; Because it requires registers set in proc's prologue
; which we omit.
;D8 B1 @ D4 E9 01 01 ?4 84 F8 23 60 {
;	proc init_error
;}

; place this to empty block, or append to the end of fw
{
	proc my_code
	
	CMP R0, 64 ; only handle our specific code
	BNE ret

	MOV R5, R0 ; save

	; write state-code 6 (but R0/R5 still have 64,
	; so after returning Switch op will just finish proc for now)
	MOV R0, 6
	db 84 F8 23 00 ; STRB.W R0, [R4, 0x23]

	; send CSCS
	db D4 E9 01 01 ; LDRD.W R0, R1, [R4, 4]
	MOV R2, 0x10 ; string length
	ADR R3, szCommand
	BL HFRE_send
	; here we could check return code, but will not do this (see above for reason)
	
	MOV R0, R5 ; restore

	ret:
	; re-execute overriten operations
	db 91 B0 ; SUB SP, SP, 0x44
	db 80 1E ; SUB R0, R0, 2
	B.W continue

	; data block:
	ALIGN 4
	szCommand:
	DCB "AT+CSCS=\"UTF-8\"\r" 00
}