loadtools/scripts: gtm900.config renamed to gen4.config It turns out that a GTM900 variant exists with 8 MiB flash, thus -h gen8 needs to be used for GTM900 modules as the general case, and the old -h gtm900 config is best renamed to -h gen4, although not currently official for any actual target.

	.text
	.code	32
	.globl	strlen
strlen:
	mov	r1, r0
1:	ldrb	r2, [r0], #1
	cmn	r2, #0
	bne	1b
	sbc	r0, r0, r1
	bx	lr