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/****************************************************************************
* arch/sim/src/up_romgetc.c
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <nuttx/arch.h>
#ifdef CONFIG_ARCH_ROMGETC
/****************************************************************************
* Private Definitions
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: up_romgetc
*
* Description:
* In Harvard architectures, data accesses and instruction accesses occur
* on different busses, perhaps concurrently. All data accesses are
* performed on the data bus unless special machine instructions are
* used to read data from the instruction address space. Also, in the
* typical MCU, the available SRAM data memory is much smaller that the
* non-volatile FLASH instruction memory. So if the application requires
* many constant strings, the only practical solution may be to store
* those constant strings in FLASH memory where they can only be accessed
* using architecture-specific machine instructions.
*
* A similar case is where strings are retained in "external" memory such
* as EEPROM or serial FLASH. This case is similar only in that again
* special operations are required to obtain the string data; it cannot
* be accessed directly from a string pointer.
*
* If CONFIG_ARCH_ROMGETC is defined, then the architecture logic must
* export the function up_romgetc(). up_romgetc() will simply read one
* byte of data from the instruction space.
*
* If CONFIG_ARCH_ROMGETC, certain C stdio functions are effected: (1)
* All format strings in printf, fprintf, sprintf, etc. are assumed to
* lie in FLASH (string arguments for %s are still assumed to reside in
* SRAM). And (2), the string argument to puts and fputs is assumed to
* reside in FLASH. Clearly, these assumptions may have to modified for
* the particular needs of your environment. There is no "one-size-fits-all"
* solution for this problem.
*
****************************************************************************/
char up_romgetc(FAR const char *ptr)
{
/* This is basically a No-Op if enabled in the simulation environment */
return *ptr;
}
#endif
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