avr: started working on hardware-based UART module.

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
+
+
+
+
+
+