From 3633bb03fcc9c281aeca45c459a5999af34cb396 Mon Sep 17 00:00:00 2001
From: Martin Preuss <martin@aquamaniac.de>
Date: Wed, 15 Jan 2025 00:12:06 +0100
Subject: [PATCH] avr: started working on hardware-based UART module.

---
 avr/modules/uart_hw/0BUILD       | 11 +++++
 avr/modules/uart_hw/defs.asm     | 49 ++++++++++++++++++++++
 avr/modules/uart_hw/lowlevel.asm | 72 ++++++++++++++++++++++++++++++++
 3 files changed, 132 insertions(+)
 create mode 100644 avr/modules/uart_hw/0BUILD
 create mode 100644 avr/modules/uart_hw/defs.asm
 create mode 100644 avr/modules/uart_hw/lowlevel.asm

diff --git a/avr/modules/uart_hw/0BUILD b/avr/modules/uart_hw/0BUILD
new file mode 100644
index 0000000..443b708
--- /dev/null
+++ b/avr/modules/uart_hw/0BUILD
@@ -0,0 +1,11 @@
+<?xml?>
+
+<gwbuild>
+
+  <extradist>
+    defs.asm
+  </extradist>
+
+</gwbuild>
+
+
diff --git a/avr/modules/uart_hw/defs.asm b/avr/modules/uart_hw/defs.asm
new file mode 100644
index 0000000..96ab2d0
--- /dev/null
+++ b/avr/modules/uart_hw/defs.asm
@@ -0,0 +1,49 @@
+; ***************************************************************************
+; copyright   : (C) 2025 by Martin Preuss
+; email       : martin@libchipcard.de
+;
+; ***************************************************************************
+; * This file is part of the project "AqHome".                              *
+; * Please see toplevel file COPYING of that project for license details.   *
+; ***************************************************************************
+
+
+.equ UART_HW_STATE_OFF                 = 0
+.equ UART_HW_STATE_IDLE                = 1
+.equ UART_HW_STATE_READING             = 2
+.equ UART_HW_STATE_WRITING             = 3
+.equ UART_HW_STATE_SKIPPING            = 4
+
+.equ UART_HW_IFACE_MSGIDBUF_SIZE       = 8
+.equ UART_HW_IFACE_READBUF_SIZE        = 24
+
+
+.equ UART_HW_IFACE_OFFS_STATE          = 0
+
+.equ UART_HW_IFACE_OFFS_READBUFFERNUM  = 1  ; num of buffer currently read
+.equ UART_HW_IFACE_OFFS_READBUFFERPOS  = 2  ; current pos in readbuffer
+.equ UART_HW_IFACE_OFFS_READBUFFERLEFT = 3  ; bytes left to read for current message
+
+.equ UART_HW_IFACE_OFFS_WRITEBUFFERID  = 4  ; num of buffer currently written from to network
+.equ UART_HW_IFACE_OFFS_WRITEBUFFERPOS = 5  ; current pos in writebuffer
+.equ UART_HW_IFACE_OFFS_WRITEBUFFERLEFT= 6  ; bytes left to write for current message
+
+
+.equ UART_HW_IFACE_OFFS_RINGBUF_USED   = 7  ; ringbuffer for incoming chars
+.equ UART_HW_IFACE_OFFS_RINGBUF_RDPOS  = 8
+.equ UART_HW_IFACE_OFFS_RINGBUF_WRPOS  = 9
+
+.equ UART_HW_IFACE_OFFS_MSGIDBUF_USED  = 10 ; ringbuffer for ids of outbound messages
+.equ UART_HW_IFACE_OFFS_MSGIDBUF_RDPOS = 11
+.equ UART_HW_IFACE_OFFS_MSGIDBUF_WRPOS = 12
+.equ UART_HW_IFACE_OFFS_RINGBUF_DATA   = 13
+.equ UART_HW_IFACE_OFFS_MSGIDBUF_DATA  = UART_HW_IFACE_OFFS_RINGBUF_DATA+UART_HW_IFACE_READBUF_SIZE
+
+.equ UART_HW_IFACE_SIZE                = UART_HW_IFACE_OFFS_MSGIDBUF_DATA+UART_HW_IFACE_MSGIDBUF_SIZE
+
+
+.equ UART_HW_IFACE_FN_ISR_CHECKATTN    = 0
+.equ UART_HW_IFACE_FN_ISR_READCHAR     = 1
+.equ UART_HW_IFACE_FN_ISR_WRITECHAR    = 2
+.equ UART_HW_IFACE_FN_COUNT            = 3
+
diff --git a/avr/modules/uart_hw/lowlevel.asm b/avr/modules/uart_hw/lowlevel.asm
new file mode 100644
index 0000000..ff2f527
--- /dev/null
+++ b/avr/modules/uart_hw/lowlevel.asm
@@ -0,0 +1,72 @@
+; ***************************************************************************
+; copyright   : (C) 2025 by Martin Preuss
+; email       : martin@libchipcard.de
+;
+; ***************************************************************************
+; * This file is part of the project "AqHome".                              *
+; * Please see toplevel file COPYING of that project for license details.   *
+; ***************************************************************************
+
+
+
+.cseg
+
+
+
+; ---------------------------------------------------------------------------
+; @routine UART_HW_InitInterface @global
+;
+; @param Y pointer to interface data in SRAM (see @ref UART_HW_IFACE_OFFS_STATE)
+; @param Z pointer to IFACE jump table for the given interface
+; @clobbers R16, R17, X
+
+UART_HW_InitInterface:
+  mov xl, yl
+  mov xh, yh
+  ldi r17, UART_HW_IFACE_SIZE
+  clr r16
+  rcall Utils_FillSram         ; (R17, X)
+  m_ringbuffer_y_reset UART_HW_IFACE_READBUF_SIZE, \
+                       UART_HW_IFACE_OFFS_RINGBUF_USED, \
+                       UART_HW_IFACE_OFFS_RINGBUF_RDPOS, \
+                       UART_HW_IFACE_OFFS_RINGBUF_WRPOS, \
+                       UART_HW_IFACE_OFFS_RINGBUF_DATA
+  m_ringbuffer_y_reset UART_HW_IFACE_MSGIDBUF_SIZE, \
+                       UART_HW_IFACE_OFFS_MSGIDBUF_USED, \
+                       UART_HW_IFACE_OFFS_MSGIDBUF_RDPOS, \
+                       UART_HW_IFACE_OFFS_MSGIDBUF_WRPOS, \
+                       UART_HW_IFACE_OFFS_MSGIDBUF_DATA
+  ldi r16, 0xff
+  std Y+UART_HW_IFACE_OFFS_READBUFFERNUM, r16
+  ret
+; @end
+
+
+
+; ---------------------------------------------------------------------------
+; @routine UART_HW_JumpToFunction @global
+;
+; @param R16 function number (see @ref UART_HW_IFACE_FN_ISR_CHECKATTN)
+; @param Y pointer to interface data in SRAM (see @ref UART_HW_IFACE_OFFS_STATE)
+; @param Z pointer to IFACE jump table for the given interface
+; @clobbers R16, R17, X
+
+UART_HW_JumpToFunction:
+  cpi r16, UART_HW_IFACE_FN_COUNT
+  brcc UART_HW_JumpToFunction_ret ; return with cleared CFLAG
+  mov xl, zl
+  mov xh, zh
+  add xl, r16
+  adc xh, xl
+  sub xh, xl
+  push xl
+  push xh
+UART_HW_JumpToFunction_ret:
+  ret ; indirect jump to address we just pushed onto the stack or return on error
+; @end
+
+
+
+
+
+