avionic design with actual uboot and tooling

submodule of avionic design uboot bootloader and with included tools to
get you started , read readme.md and readme-tk1-loader.md

u-boot/arch/nios2/cpu/exceptions.S

@@ -0,0 +1,139 @@
+/*
+ * (C) Copyright 2004, Psyent Corporation <www.psyent.com>
+ * Scott McNutt <smcnutt@psyent.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <config.h>
+#include <asm/opcodes.h>
+
+
+	.text
+	.align	4
+
+	.global _exception
+
+	.set noat
+	.set nobreak
+
+_exception:
+	/* SAVE ALL REGS -- this allows trap and unimplemented
+	 * instruction handlers to be coded conveniently in C
+	 */
+	addi	sp, sp, -(33*4)
+	stw	r0, 0(sp)
+	stw	r1, 4(sp)
+	stw	r2, 8(sp)
+	stw	r3, 12(sp)
+	stw	r4, 16(sp)
+	stw	r5, 20(sp)
+	stw	r6, 24(sp)
+	stw	r7, 28(sp)
+	stw	r8, 32(sp)
+	stw	r9, 36(sp)
+	stw	r10, 40(sp)
+	stw	r11, 44(sp)
+	stw	r12, 48(sp)
+	stw	r13, 52(sp)
+	stw	r14, 56(sp)
+	stw	r15, 60(sp)
+	stw	r16, 64(sp)
+	stw	r17, 68(sp)
+	stw	r19, 72(sp)
+	stw	r19, 76(sp)
+	stw	r20, 80(sp)
+	stw	r21, 84(sp)
+	stw	r22, 88(sp)
+	stw	r23, 92(sp)
+	stw	r24, 96(sp)
+	stw	r25, 100(sp)
+	stw	r26, 104(sp)
+	stw	r27, 108(sp)
+	stw	r28, 112(sp)
+	stw	r29, 116(sp)
+	stw	r30, 120(sp)
+	stw	r31, 124(sp)
+	rdctl	et, estatus
+	stw	et, 128(sp)
+
+	/* If interrupts are disabled -- software interrupt */
+	rdctl	et, estatus
+	andi	et, et, 1
+	beq	et, r0, 0f
+
+	/* If no interrupts are pending -- software interrupt */
+	rdctl	et, ipending
+	beq	et, r0, 0f
+
+	/* HARDWARE INTERRUPT: Call interrupt handler */
+	movhi	r3, %hi(external_interrupt)
+	ori	r3, r3, %lo(external_interrupt)
+	mov	r4, sp		/* ptr to regs */
+	callr	r3
+
+	/* Return address fixup: execution resumes by re-issue of
+	 * interrupted instruction at ea-4 (ea == r29). Here we do
+	 * simple fixup to allow common exception return.
+	 */
+	ldw	r3, 116(sp)
+	addi	r3, r3, -4
+	stw	r3, 116(sp)
+	br	_exception_return
+
+0:
+	/* TRAP EXCEPTION */
+	movhi	r3, %hi(OPC_TRAP)
+	ori	r3, r3, %lo(OPC_TRAP)
+	addi	r1, ea, -4
+	ldw	r1, 0(r1)
+	bne	r1, r3, 1f
+	movhi	r3, %hi(trap_handler)
+	ori	r3, r3, %lo(trap_handler)
+	mov	r4, sp		/* ptr to regs */
+	callr	r3
+	br	_exception_return
+
+1:
+	/* UNIMPLEMENTED INSTRUCTION EXCEPTION */
+	movhi	r3, %hi(soft_emulation)
+	ori	r3, r3, %lo(soft_emulation)
+	mov	r4, sp		/* ptr to regs */
+	callr	r3
+
+	/* Restore regsisters and return from exception*/
+_exception_return:
+	ldw	r1, 4(sp)
+	ldw	r2, 8(sp)
+	ldw	r3, 12(sp)
+	ldw	r4, 16(sp)
+	ldw	r5, 20(sp)
+	ldw	r6, 24(sp)
+	ldw	r7, 28(sp)
+	ldw	r8, 32(sp)
+	ldw	r9, 36(sp)
+	ldw	r10, 40(sp)
+	ldw	r11, 44(sp)
+	ldw	r12, 48(sp)
+	ldw	r13, 52(sp)
+	ldw	r14, 56(sp)
+	ldw	r15, 60(sp)
+	ldw	r16, 64(sp)
+	ldw	r17, 68(sp)
+	ldw	r19, 72(sp)
+	ldw	r19, 76(sp)
+	ldw	r20, 80(sp)
+	ldw	r21, 84(sp)
+	ldw	r22, 88(sp)
+	ldw	r23, 92(sp)
+	ldw	r24, 96(sp)
+	ldw	r25, 100(sp)
+	ldw	r26, 104(sp)
+	ldw	r27, 108(sp)
+	ldw	r28, 112(sp)
+	ldw	r29, 116(sp)
+	ldw	r30, 120(sp)
+	ldw	r31, 124(sp)
+	addi	sp, sp, (33*4)
+	eret
+/*-------------------------------------------------------------*/