/* Copyright (C) 2019  Adam Green (https://github.com/adamgreen)

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/
#include "CrashCatcherPriv.h"

/* Implementation of ARMv7-M assembly language code to trap exceptions and call CrashCatcher_Entry(). */
    .text
    .syntax unified
    .arch armv7-m

    /* Called on Hard Fault exception.  Stacks important registers and calls CrashCatcher_Entry().

        extern "C" void HardFault_Handler(void);
    */
    .global HardFault_Handler
    .type HardFault_Handler, %function
    .thumb_func
HardFault_Handler:
    /* Push the following onto the stack (see CrashCatcherExceptionRegisters structure). The g_crashCatcherStack buffer
       is reserved for use as the stack while CrashCatcher is running.
        msp
        psp
        exceptionPSR
        r4
        r5
        r6
        r7
        r8
        r9
        r10
        r11
        exceptionLR */
    // Prevent double fault
    ldr r0, = crash_orig_stack
    ldr r0, [r0]
    cmp r0, #0
    bne .

    // Create stack for CrashCatcher
    mrs     r3, xpsr
    mrs     r2, psp
    mrs     r1, msp
    ldr     sp, =(g_crashCatcherStack + 4 * CRASH_CATCHER_STACK_WORD_COUNT)
    push.w  {r1-r11,lr}

    // Call original console dump
    ldr r0,=crash_orig_stack
    str sp, [r0]
    mov sp, r1

    ldr r0,=crash_orig_stack
    ldr sp, [r0]

    // Call CrashCatcher_Entry with first argument pointing to registers that were just stacked.
    mov     r0, sp
    ldr r2,=CrashCatcher_Entry  // Stack frame exception return
    mrs r3, psp
    str r2, [r3, #0x18]
    str r0, [r3]
    orr lr, lr, #4        // Back to user stack
    orr lr, lr, #8        // Back to user mode
    bx lr                 // Return from exception and jump to the CatchCatcher_Entry
    b .


    // Let assembler know that we have hit the end of the HardFault_Handler function.
    .pool
    .size   HardFault_Handler, .-HardFault_Handler



    /* Called from CrashCatcher core to copy all floating point registers to supplied buffer. The supplied buffer must
       be large enough to contain 33 32-bit values (S0-S31 & FPSCR).

        void CrashCatcher_CopyAllFloatingPointRegisters(uint32_t* pBuffer);
    */
    .global CrashCatcher_CopyAllFloatingPointRegisters
    .type CrashCatcher_CopyAllFloatingPointRegisters, %function
    .thumb_func
CrashCatcher_CopyAllFloatingPointRegisters:
#if CRASH_CATCHER_WITH_FPU
    // Grab a copy of FPSCR before issuing any other FP instructions.
    vmrs        r1, fpscr

    // Move s0 - s31 to pBuffer.
    vstmia.32   r0!, {s0 - s31}

    // Move fpscr to pBuffer.
    str         r1, [r0]
#endif
    // Return to caller.
    bx          lr

    .pool
    .size   CrashCatcher_CopyAllFloatingPointRegisters, .-CrashCatcher_CopyAllFloatingPointRegisters



    /* Called from CrashCatcher core to copy upper 16 floating point registers to supplied buffer. The supplied buffer
       must be large enough to contain 16 32-bit values (S16-S31).

        void CrashCatcher_CopyUpperFloatingPointRegisters(uint32_t* pBuffer);
    */
    .global CrashCatcher_CopyUpperFloatingPointRegisters
    .type CrashCatcher_CopyUpperFloatingPointRegisters, %function
    .thumb_func
CrashCatcher_CopyUpperFloatingPointRegisters:
#if CRASH_CATCHER_WITH_FPU
    // Move s16 - s31 to pBuffer.
    vstmia.32   r0!, {s16 - s31}
#endif
    // Return to caller.
    bx      lr

    .pool
    .size   CrashCatcher_CopyUpperFloatingPointRegisters, .-CrashCatcher_CopyUpperFloatingPointRegisters



    .data
    crash_orig_stack: .long 0