;**************************************************************************
; arch/z80/src/ez80/ez80_vectors.asm
;
; Copyright (C) 2008-2009 Gregory Nutt. All rights reserved.
; Author: Gregory Nutt <gnutt@nuttx.org>
;
; Redistribution and use in source and binary forms, with or without
; modification, are permitted provided that the following conditions
; are met:
;
; 1. Redistributions of source code must retain the above copyright
; notice, this list of conditions and the following disclaimer.
; 2. Redistributions in binary form must reproduce the above copyright
; notice, this list of conditions and the following disclaimer in
; the documentation and/or other materials provided with the
; distribution.
; 3. Neither the name NuttX nor the names of its contributors may be
; used to endorse or promote products derived from this software
; without specific prior written permission.
;
; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
; FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
; COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
; BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
; OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
; AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
; LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
; ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
; POSSIBILITY OF SUCH DAMAGE.
;
;**************************************************************************
;**************************************************************************
; Constants
;**************************************************************************
NVECTORS EQU 64 ; max possible interrupt vectors
;* Bits in the Z80 FLAGS register *****************************************
EZ80_C_FLAG EQU 01h ; Bit 0: Carry flag
EZ80_N_FLAG EQU 02h ; Bit 1: Add/Subtract flag
EZ80_PV_FLAG EQU 04h ; Bit 2: Parity/Overflow flag
EZ80_H_FLAG EQU 10h ; Bit 4: Half carry flag
EZ80_Z_FLAG EQU 40h ; Bit 5: Zero flag
EZ80_S_FLAG EQU 80h ; Bit 7: Sign flag
;* The IRQ number to use for unused vectors
EZ80_UNUSED EQU 40h
;**************************************************************************
; Global Symbols Imported
;**************************************************************************
xref _ez80_startup
xref _up_doirq
;**************************************************************************
; Global Symbols Exported
;**************************************************************************
xdef _ez80_reset
xdef _ez80_initvectors
xdef _ez80_handlers
xdef _ez80_rstcommon
xdef _ez80_initvectors
xdef _ez80_vectable
;**************************************************************************
; Macros
;**************************************************************************
; Define one reset handler
; 1. Disable interrupts
; 2. Dlear mixed memory mode (MADL) flag
; 3. jump to initialization procedure with jp.lil to set ADL
rstvector: macro
di
rsmix
jp.lil _ez80_startup
endmac rstvector
; Define one interrupt handler
irqhandler: macro vectno
; Save AF on the stack, set the interrupt number and jump to the
; common reset handling logic.
; Offset 8: Return PC is already on the stack
push af ; Offset 7: AF (retaining flags)
ld a, #vectno ; A = vector number
jp _ez80_rstcommon ; Remaining RST handling is common
endmac irqhandler
;**************************************************************************
; Reset entry points
;**************************************************************************
define .RESET, space = ROM
segment .RESET
_ez80_reset:
_rst0:
rstvector
_rst8:
rstvector
_rst10:
rstvector
_rst18:
rstvector
_rst20:
rstvector
_rst28:
rstvector
_rst30:
rstvector
_rst38:
rstvector
ds %26
_nmi:
retn
;**************************************************************************
; Startup logic
;**************************************************************************
define .STARTUP, space = ROM
segment .STARTUP
.assume ADL=1
;**************************************************************************
; Interrupt Vector Handling
;**************************************************************************
; Symbol Val VecNo Addr
;----------------- --- ----- -----
_ez80_handlers:
irqhandler 0 ; EZ80_EMACRX_IRQ 0 0 0x040
handlersize equ $-_ez80handlers
irqhandler 1 ; EZ80_EMACTX_IRQ 1 1 0x044
irqhandler 2 ; EZ80_EMACSYS_IRQ 2 2 0x048
irqhandler 3 ; EZ80_PLL_IRQ 3 3 0x04c
irqhandler 4 ; EZ80_FLASH_IRQ 4 4 0x050
irqhandler 5 ; EZ80_TIMER0_IRQ 5 5 0x054
irqhandler 6 ; EZ80_TIMER1_IRQ 6 6 0x058
irqhandler 7 ; EZ80_TIMER2_IRQ 7 7 0x05c
irqhandler 8 ; EZ80_TIMER3_IRQ 8 8 0x060
irqhandler EZ80_UNUSED ; 9 0x064
irqhandler EZ80_UNUSED+1 ; 10 0x068
irqhandler 9 ; EZ80_RTC_IRQ 9 11 0x06C
irqhandler 10 ; EZ80_UART0_IRQ 10 12 0x070
irqhandler 11 ; EZ80_UART1_IRQ 11 13 0x074
irqhandler 12 ; EZ80_I2C_IRQ 12 14 0x078
irqhandler 13 ; EZ80_SPI_IRQ 13 15 0x07c
irqhandler 14 ; EZ80_PORTA0_IRQ 14 16 0x080
irqhandler 15 ; EZ80_PORTA1_IRQ 15 17 0x084
irqhandler 16 ; EZ80_PORTA2_IRQ 16 18 0x088
irqhandler 17 ; EZ80_PORTA3_IRQ 17 19 0x08c
irqhandler 18 ; EZ80_PORTA4_IRQ 18 20 0x090
irqhandler 19 ; EZ80_PORTA5_IRQ 19 21 0x094
irqhandler 20 ; EZ80_PORTA6_IRQ 20 22 0x098
irqhandler 21 ; EZ80_PORTA7_IRQ 21 23 0x09c
irqhandler 22 ; EZ80_PORTB0_IRQ 22 24 0x0a0
irqhandler 23 ; EZ80_PORTB1_IRQ 23 25 0x0a4
irqhandler 24 ; EZ80_PORTB2_IRQ 24 26 0x0a8
irqhandler 25 ; EZ80_PORTB3_IRQ 25 27 0x0ac
irqhandler 26 ; EZ80_PORTB4_IRQ 26 28 0x0b0
irqhandler 27 ; EZ80_PORTB5_IRQ 27 29 0x0b4
irqhandler 28 ; EZ80_PORTB6_IRQ 28 20 0x0b8
irqhandler 29 ; EZ80_PORTB7_IRQ 29 21 0x0bc
irqhandler 30 ; EZ80_PORTC0_IRQ 30 22 0x0c0
irqhandler 31 ; EZ80_PORTC1_IRQ 31 23 0x0c4
irqhandler 32 ; EZ80_PORTC2_IRQ 32 24 0x0c8
irqhandler 33 ; EZ80_PORTC3_IRQ 33 25 0x0cc
irqhandler 34 ; EZ80_PORTC4_IRQ 34 26 0x0d0
irqhandler 35 ; EZ80_PORTC5_IRQ 35 27 0x0d4
irqhandler 36 ; EZ80_PORTC6_IRQ 36 28 0x0d8
irqhandler 37 ; EZ80_PORTC7_IRQ 37 29 0x0dc
irqhandler 38 ; EZ80_PORTD0_IRQ 38 40 0x0e0
irqhandler 39 ; EZ80_PORTD1_IRQ 39 41 0x0e4
irqhandler 40 ; EZ80_PORTD2_IRQ 40 42 0x0e8
irqhandler 41 ; EZ80_PORTD3_IRQ 41 43 0x0ec
irqhandler 42 ; EZ80_PORTD4_IRQ 42 44 0x0f0
irqhandler 43 ; EZ80_PORTD5_IRQ 43 45 0x0f4
irqhandler 44 ; EZ80_PORTD6_IRQ 44 46 0x0f8
irqhandler 45 ; EZ80_PORTD7_IRQ 45 47 0x0fc
irqhandler EZ80_UNUSED+1 ; 48 0x100
irqhandler EZ80_UNUSED+2 ; 49 0x104
irqhandler EZ80_UNUSED+3 ; 50 0x108
irqhandler EZ80_UNUSED+4 ; 51 0x10c
irqhandler EZ80_UNUSED+5 ; 52 0x110
irqhandler EZ80_UNUSED+6 ; 53 0x114
irqhandler EZ80_UNUSED+7 ; 54 0x118
irqhandler EZ80_UNUSED+8 ; 55 0x11c
irqhandler EZ80_UNUSED+9 ; 56 0x120
irqhandler EZ80_UNUSED+10 ; 57 0x124
irqhandler EZ80_UNUSED+11 ; 58 0x128
irqhandler EZ80_UNUSED+12 ; 59 0x12c
irqhandler EZ80_UNUSED+13 ; 60 0x130
irqhandler EZ80_UNUSED+14 ; 61 0x134
irqhandler EZ80_UNUSED+15 ; 62 0x138
irqhandler EZ80_UNUSED+16 ; 63 0x13c
;**************************************************************************
; Common Interrupt handler
;**************************************************************************
_ez80_rstcommon:
; Create a register frame. SP points to top of frame + 4, pushes
; decrement the stack pointer. Already have
;
; Offset 8: Return PC is already on the stack
; Offset 7: AF (retaining flags)
;
; IRQ number is in A
push hl ; Offset 6: HL
ld hl, #(3*3) ; HL is the value of the stack pointer before
add hl, sp ; the interrupt occurred (3 for PC, AF, HL)
push hl ; Offset 5: Stack pointer
push iy ; Offset 4: IY
push ix ; Offset 3: IX
push de ; Offset 2: DE
push bc ; Offset 1: BC
; At this point, we know that interrupts were enabled (or we wouldn't be here
; so we can save a fake indicationn that will cause interrupts to restored when
; this context is restored
ld bc, #EZ80_PV_FLAG ; Parity bit. 1=parity odd, IEF2=1
push bc ; Offset 0: I with interrupt state in parity
di ; (not necessary)
; Call the interrupt decode logic. SP points to the beggining of the reg structure
ld hl, #0 ; Argument #2 is the beginning of the reg structure
add hl, sp ;
push hl ; Place argument #2 at the top of stack
ld bc, #0 ; BC = reset number
ld c, a ; Save the reset number in C
push bc ; Argument #1 is the Reset number
call _up_doirq ; Decode the IRQ
; On return, HL points to the beginning of the reg structure to restore
; Note that (1) the arguments pushed on the stack are not popped, and (2) the
; original stack pointer is lost. In the normal case (no context switch),
; HL will contain the value of the SP before the arguments were pushed.
ld sp, hl ; Use the new stack pointer
; Restore registers. HL points to the beginning of the reg structure to restore
ex af, af' ; Select alternate AF
pop af ; Offset 0: AF' = I with interrupt state in parity
ex af, af' ; Restore original AF
pop bc ; Offset 1: BC
pop de ; Offset 2: DE
pop ix ; Offset 3: IX
pop iy ; Offset 4: IY
exx ; Use alternate BC/DE/HL
pop hl ; Offset 5: HL' = Stack pointer after return
exx ; Restore original BC/DE/HL
pop hl ; Offset 6: HL
pop af ; Offset 7: AF
; Restore the stack pointer
exx ; Use alternate BC/DE/HL
pop de ; Offset 8: Return address
ld sp, hl ; Set SP = saved stack pointer value before return
push de ; Set up for reti
exx ; Restore original BC/DE/HL
; Restore interrupt state
ex af, af' ; Recover interrupt state
jp po, nointenable ; Odd parity, IFF2=0, means disabled
ex af, af' ; Restore AF (before enabling interrupts)
ei ; yes
reti
nointenable:
ex af, af' ; Restore AF
reti
;**************************************************************************
; Vector Setup Logic
;**************************************************************************
_ez80_initvectors:
; Initialize the vector table
ld iy, _ez80_vectable
ld ix, 4
ld bc, 4
ld b, NVECTORS
xor a, a ; Clear carry
ld hl, handlersize
ld de, _ez80_handlers
sbc hl, de ; Length of irq handler in hl
ld d, h
ld e, l
ld hl, _ez80_handlers ; Start of handlers in hl
ld a, 0
$1:
ld (iy), hl ; Store IRQ handler
ld (iy+3), a ; Pad to 4 bytes
add hl, de ; Point to next handler
push de
ld de, 4
add iy, de ; Point to next entry in vector table
pop de
djnz $1 ; Loop until all vectors have been written
; Select interrupt mode 2
im 2 ; Interrupt mode 2
; Write the address of the vector table into the interrupt vector base
ld hl, _ez80_vectable >> 8
ld i, hl
ret
;**************************************************************************
; Vector Table
;**************************************************************************
; This segment must be aligned on a 512 byte boundary anywhere in RAM
; Each entry will be a 3-byte address in a 4-byte space
define .IVECTS, space = RAM, align = 200h
segment .IVECTS
; The first 64 bytes are not used... the vectors actually start at +0x40
_ez80_vecreserve:
ds 64
_ez80_vectable:
ds NVECTORS * 4
