Lpc2000

Kasper,

I will not comment every line, but a bit

>> 	.macro SC_TFUNC name
>> 	.text
>> 	.code 16
>> 	.thumb_func
>> 	.globl name
>> name:
>> 	.endm

Simply a macro for my lazy fingers ...

BTW: Get hands on ARM ARM and read it carefully. You will meet assembly 
anyway :-)

>> 	SC_TFUNC sc_sysLock
>> 	bx	pc
>> 	nop
>> 	.code 32
>> 	.globl	sc_sysLock_a
>> sc_sysLock_a:
>> 	mrs	r0,cpsr
>> 	orr	r1,r0,#PSR_I_BIT
>> 	msr	cpsr_c,r1
>> 	bx	lr

Disable interrupts and returns the old PSR in R0 in order to restore it 
later.
The bx pc; nop is a veneer to change from Thumb to ARM mode.

>> 	SC_TFUNC sc_sysUnlock
>> 	bx	pc
>> 	nop
>> 	.code 32
>> 	.globl	sc_sysUnlock_a
>> sc_sysUnlock_a:
>> 	and	r0,r0,#PSR_I_BIT
>> 	mrs	r1,cpsr
>> 	bic	r1,r1,#PSR_I_BIT
>> 	orr	r1,r1,r0
>> 	msr	cpsr_c,r1
>> 	bx	lr

This _restores_ the I bit with the value stored in R0.

Restore because , sc_sysLock() might be called with interrupts already 
disabled.

> Thanks very much for your answer. Sorry but I do not know asm so
> could you please explain what happens in every line and is the above
> ready to insert in my existing C-code?

Put it in lock.S (or any other file, but with capital S) and compile it
(with gcc !). Add prototypes to your C code. Use it.
You may inline it, but _I_ use inline only in very rare situations.


-- 
42Bastian Schick