fernly: Remove GPL-2 files, move to libgcc

We used to use source files taken from U-Boot to allow for division and
modular arithmetic.  With the move to a BSD license, this is no longer
acceptible.

As a workaround, use a libgcc taken from a standard gcc distribution.
Add the .a file, which has not been modified in any way.

Signed-off-by: Sean Cross <xobs@kosagi.com>

Makefile

@@ -6,7 +6,7 @@ CFLAGS = -march=armv5te -mfloat-abi=soft -Wall \
 AFLAGS = 
 
 LDFLAGS = --nostdlib -T fernvale.ld
-LIBS =
+LIBS = lib/libgcc-armv5.a
 
 SRC_C = \
 	bionic.c \
@@ -38,9 +38,6 @@ SRC_S = \
 	scriptic/spi.S \
 	scriptic/spi-blockmode.S \
 	scriptic/keypad.S \
-	_lshrdi3.S \
-	_udivsi3.S \
-	_divsi3.S \
 	start.S
 
 OBJ = $(addprefix $(BUILD)/, $(SRC_S:.S=.o) $(SRC_C:.c=.o))

README.md

@@ -92,6 +92,23 @@ That is, send the following packet:
 | 00 00 |
 
 
+Licensing
+---------
+
+Fernly is licensed under the BSD 2-clause license (see LICENSE).
+
+Previous versions of fernly linked against division libraries taken from U-Boot,
+which were licensed under GPL-2.  These files have been removed.
+
+Instead, we supply a version of libgcc.a.  This file was extracted from a
+standard gcc toolchain, specifically:
+
+    https://code.google.com/p/yus-repo/downloads/detail?name=arm-none-eabi-4.6-armv5.tar.gz
+
+It has not been modified, and its distribution here should be covered under
+the "runtime exception".
+
+
 Memory Map
 ----------
 

_divsi3.S

@@ -1,142 +0,0 @@
-
-.macro ARM_DIV_BODY dividend, divisor, result, curbit
-
-#if __LINUX_ARM_ARCH__ >= 5
-
-	clz	\curbit, \divisor
-	clz	\result, \dividend
-	sub	\result, \curbit, \result
-	mov	\curbit, #1
-	mov	\divisor, \divisor, lsl \result
-	mov	\curbit, \curbit, lsl \result
-	mov	\result, #0
-
-#else
-
-	@ Initially shift the divisor left 3 bits if possible,
-	@ set curbit accordingly.  This allows for curbit to be located
-	@ at the left end of each 4 bit nibbles in the division loop
-	@ to save one loop in most cases.
-	tst	\divisor, #0xe0000000
-	moveq	\divisor, \divisor, lsl #3
-	moveq	\curbit, #8
-	movne	\curbit, #1
-
-	@ Unless the divisor is very big, shift it up in multiples of
-	@ four bits, since this is the amount of unwinding in the main
-	@ division loop.  Continue shifting until the divisor is
-	@ larger than the dividend.
-1:	cmp	\divisor, #0x10000000
-	cmplo	\divisor, \dividend
-	movlo	\divisor, \divisor, lsl #4
-	movlo	\curbit, \curbit, lsl #4
-	blo	1b
-
-	@ For very big divisors, we must shift it a bit at a time, or
-	@ we will be in danger of overflowing.
-1:	cmp	\divisor, #0x80000000
-	cmplo	\divisor, \dividend
-	movlo	\divisor, \divisor, lsl #1
-	movlo	\curbit, \curbit, lsl #1
-	blo	1b
-
-	mov	\result, #0
-
-#endif
-
-	@ Division loop
-1:	cmp	\dividend, \divisor
-	subhs	\dividend, \dividend, \divisor
-	orrhs	\result,   \result,   \curbit
-	cmp	\dividend, \divisor,  lsr #1
-	subhs	\dividend, \dividend, \divisor, lsr #1
-	orrhs	\result,   \result,   \curbit,  lsr #1
-	cmp	\dividend, \divisor,  lsr #2
-	subhs	\dividend, \dividend, \divisor, lsr #2
-	orrhs	\result,   \result,   \curbit,  lsr #2
-	cmp	\dividend, \divisor,  lsr #3
-	subhs	\dividend, \dividend, \divisor, lsr #3
-	orrhs	\result,   \result,   \curbit,  lsr #3
-	cmp	\dividend, #0			@ Early termination?
-	movnes	\curbit,   \curbit,  lsr #4	@ No, any more bits to do?
-	movne	\divisor,  \divisor, lsr #4
-	bne	1b
-
-.endm
-
-.macro ARM_DIV2_ORDER divisor, order
-
-#if __LINUX_ARM_ARCH__ >= 5
-
-	clz	\order, \divisor
-	rsb	\order, \order, #31
-
-#else
-
-	cmp	\divisor, #(1 << 16)
-	movhs	\divisor, \divisor, lsr #16
-	movhs	\order, #16
-	movlo	\order, #0
-
-	cmp	\divisor, #(1 << 8)
-	movhs	\divisor, \divisor, lsr #8
-	addhs	\order, \order, #8
-
-	cmp	\divisor, #(1 << 4)
-	movhs	\divisor, \divisor, lsr #4
-	addhs	\order, \order, #4
-
-	cmp	\divisor, #(1 << 2)
-	addhi	\order, \order, #3
-	addls	\order, \order, \divisor, lsr #1
-
-#endif
-
-.endm
-
-	.align	5
-.globl __divsi3
-.globl __aeabi_idiv
-__divsi3:
-__aeabi_idiv:
-	cmp	r1, #0
-	eor	ip, r0, r1			@ save the sign of the result.
-	beq	Ldiv0
-	rsbmi	r1, r1, #0			@ loops below use unsigned.
-	subs	r2, r1, #1			@ division by 1 or -1 ?
-	beq	10f
-	movs	r3, r0
-	rsbmi	r3, r0, #0			@ positive dividend value
-	cmp	r3, r1
-	bls	11f
-	tst	r1, r2				@ divisor is power of 2 ?
-	beq	12f
-
-	ARM_DIV_BODY r3, r1, r0, r2
-
-	cmp	ip, #0
-	rsbmi	r0, r0, #0
-	mov	pc, lr
-
-10:	teq	ip, r0				@ same sign ?
-	rsbmi	r0, r0, #0
-	mov	pc, lr
-
-11:	movlo	r0, #0
-	moveq	r0, ip, asr #31
-	orreq	r0, r0, #1
-	mov	pc, lr
-
-12:	ARM_DIV2_ORDER r1, r2
-
-	cmp	ip, #0
-	mov	r0, r3, lsr r2
-	rsbmi	r0, r0, #0
-	mov	pc, lr
-
-Ldiv0:
-
-	str	lr, [sp, #-4]!
-	bl	__div0
-	mov	r0, #0			@ About as wrong as it could be.
-	ldr	pc, [sp], #4

_lshrdi3.S

@@ -1,26 +0,0 @@
-/* Copyright 1995, 1996, 1998, 1999, 2000, 2003, 2004, 2005
-   Free Software Foundation, Inc.
-
- * SPDX-License-Identifier:	GPL-2.0+
- */
-
-#ifdef __ARMEB__
-#define al r1
-#define ah r0
-#else
-#define al r0
-#define ah r1
-#endif
-
-.globl __lshrdi3
-.globl __aeabi_llsr
-__lshrdi3:
-__aeabi_llsr:
-
-	subs	r3, r2, #32
-	rsb	ip, r2, #32
-	movmi	al, al, lsr r2
-	movpl	al, ah, lsr r3
-	orrmi	al, al, ah, lsl ip
-	mov	ah, ah, lsr r2
-	mov	pc, lr

_udivsi3.S

@@ -1,93 +0,0 @@
-/* # 1 "libgcc1.S" */
-@ libgcc1 routines for ARM cpu.
-@ Division routines, written by Richard Earnshaw, (rearnsha@armltd.co.uk)
-dividend	.req	r0
-divisor		.req	r1
-result		.req	r2
-curbit		.req	r3
-/* ip		.req	r12	*/
-/* sp		.req	r13	*/
-/* lr		.req	r14	*/
-/* pc		.req	r15	*/
-	.text
-	.globl	 __udivsi3
-	.type	__udivsi3 ,function
-	.globl	__aeabi_uidiv
-	.type	__aeabi_uidiv ,function
-	.align	0
- __udivsi3:
- __aeabi_uidiv:
-	cmp	divisor, #0
-	beq	Ldiv0
-	mov	curbit, #1
-	mov	result, #0
-	cmp	dividend, divisor
-	bcc	Lgot_result
-Loop1:
-	@ Unless the divisor is very big, shift it up in multiples of
-	@ four bits, since this is the amount of unwinding in the main
-	@ division loop.  Continue shifting until the divisor is
-	@ larger than the dividend.
-	cmp	divisor, #0x10000000
-	cmpcc	divisor, dividend
-	movcc	divisor, divisor, lsl #4
-	movcc	curbit, curbit, lsl #4
-	bcc	Loop1
-Lbignum:
-	@ For very big divisors, we must shift it a bit at a time, or
-	@ we will be in danger of overflowing.
-	cmp	divisor, #0x80000000
-	cmpcc	divisor, dividend
-	movcc	divisor, divisor, lsl #1
-	movcc	curbit, curbit, lsl #1
-	bcc	Lbignum
-Loop3:
-	@ Test for possible subtractions, and note which bits
-	@ are done in the result.  On the final pass, this may subtract
-	@ too much from the dividend, but the result will be ok, since the
-	@ "bit" will have been shifted out at the bottom.
-	cmp	dividend, divisor
-	subcs	dividend, dividend, divisor
-	orrcs	result, result, curbit
-	cmp	dividend, divisor, lsr #1
-	subcs	dividend, dividend, divisor, lsr #1
-	orrcs	result, result, curbit, lsr #1
-	cmp	dividend, divisor, lsr #2
-	subcs	dividend, dividend, divisor, lsr #2
-	orrcs	result, result, curbit, lsr #2
-	cmp	dividend, divisor, lsr #3
-	subcs	dividend, dividend, divisor, lsr #3
-	orrcs	result, result, curbit, lsr #3
-	cmp	dividend, #0			@ Early termination?
-	movnes	curbit, curbit, lsr #4		@ No, any more bits to do?
-	movne	divisor, divisor, lsr #4
-	bne	Loop3
-Lgot_result:
-	mov	r0, result
-	mov	pc, lr
-Ldiv0:
-	str	lr, [sp, #-4]!
-	bl	 __div0       (PLT)
-	mov	r0, #0			@ about as wrong as it could be
-	ldmia	sp!, {pc}
-	.size  __udivsi3       , . -  __udivsi3
-
-.globl __aeabi_uidivmod
-__aeabi_uidivmod:
-
-	stmfd	sp!, {r0, r1, ip, lr}
-	bl	__aeabi_uidiv
-	ldmfd	sp!, {r1, r2, ip, lr}
-	mul	r3, r0, r2
-	sub	r1, r1, r3
-	mov	pc, lr
-
-.globl __aeabi_idivmod
-__aeabi_idivmod:
-
-	stmfd	sp!, {r0, r1, ip, lr}
-	bl	__aeabi_idiv
-	ldmfd	sp!, {r1, r2, ip, lr}
-	mul	r3, r0, r2
-	sub	r1, r1, r3
-	mov	pc, lr