view Small_CPU/CPU2-RTE.ld @ 224:ceecabfddb57 div-fixes-3

Bugfix, deco: fix 2 (small) problems with calculated ceiling This fixes 1 trivial, and 1 not really trivial bug in the calculation of the ceiling. When simulating a bounce dive to 80m, things become clear (tried this on a CCR dive, fixed setpoint 1.2bar, about 15 minutes of bottom time). Closely watch the behavior of the ceiling data. At some point during the ascent, the ceiling begins to decrease in 10cm steps. Then suddenly (while still ascending), the ceiling increases again with 1m, does not change for some time, and then suddenly steps 1.1m less deep. While not very relevant to real deco diving, it is simply wrong. The reason for this is subtle. The algorithm used to find the ceiling is a sort of linear search, stepping down a meter, overshoot the depth, and search back in 10cm steps. It seems some numerical instability. Fixing this, was a bit more computational intensive search by stepping up down in equal steps of 10cm. But, I'm pretty sure that things can be speeded up here, as a ceiling does not change fast, so it should be not that difficult to limit the search space, or use a binary search algorithm instead. The trivial second problem fixed, is that the ceiling ends at the surface and not at 1m depth. This small issue became visible after changing the step down size above. Signed-off-by: Jan Mulder <jlmulder@xs4all.nl>
author Jan Mulder <jlmulder@xs4all.nl>
date Sun, 31 Mar 2019 19:35:51 +0200
parents 321df89d5710
children aa286a4926c2
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/* ---------------------------------------------------------------------------- */
/*                  Em::Blocks embedded development Support                     */
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/* ---------------------------------------------------------------------------- */

/*------------------------------------------------------------------------------
 *      Linker script for running in internal FLASH on the STM32F401RE
 *----------------------------------------------------------------------------*/

/* Entry Point */
ENTRY(Reset_Handler)

OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
OUTPUT_ARCH(arm)
SEARCH_DIR(.)

/* Memory Spaces Definitions */
MEMORY
{
    ROM  (rx) : ORIGIN = 0x08000000, LENGTH = 512K /* 80000 */
    RAM (rwx) : ORIGIN = 0x20000000, LENGTH = 96K
}
/* Linker script to place sections and symbol values. Should be used together
 * with other linker script that defines memory regions FLASH and RAM.
 * It references following symbols, which must be defined in code:
 *   Reset_Handler : Entry of reset handler
 * 
 * It defines following symbols, which code can use without definition:
 *   __exidx_start
 *   __exidx_end
 *   __etext
 *   __data_start__
 *   __preinit_array_start
 *   __preinit_array_end
 *   __init_array_start
 *   __init_array_end
 *   __fini_array_start
 *   __fini_array_end
 *   __data_end__
 *   __bss_start__
 *   __bss_end__
 *   __end__
 *   end
 *   __HeapLimit
 *   __StackLimit
 *   __StackTop
 *   __stack
 */


SECTIONS
{
  .isr_vector 0x08000000 :
  {
  . = ALIGN(4);
    KEEP( *(.isr_vector) ) 
    KEEP(*(.init))
    KEEP(*(.fini))
  } >ROM
  
	/* Place FirmwareData at absolute address */
	.firmware_data 0x08005000:
	{
		cpu2_FirmwareData = 0; 
		KEEP( *(.firmware_data) )
	} > ROM

	.text 0x08005100 :
	{	
		. = ALIGN(4);
		*(.text)           /* .text sections (code) */
		*(.text*)
		*(.eh_frame*)
        . = ALIGN(4); 
  
	} > ROM

/********************** Constant data into ROM memory *********************/
  .rodata :
  {
    . = ALIGN(4);
    *(.rodata)         /* .rodata sections (constants, strings, etc.) */
    *(.rodata*)        /* .rodata* sections (constants, strings, etc.) */
    . = ALIGN(4);
  } >ROM
  
	.ARM.extab :
	{
		*(.ARM.extab* .gnu.linkonce.armextab.*)
	} > ROM

	__exidx_start = .;
	.ARM.exidx :
	{
		*(.ARM.exidx* .gnu.linkonce.armexidx.*)
	} > ROM
	__exidx_end = .;

  .preinit_array     :
  {
    . = ALIGN(4);
    PROVIDE_HIDDEN( __preinit_array_start = . );
    KEEP( *(.preinit_array*) )
    PROVIDE_HIDDEN( __preinit_array_end = . );
    . = ALIGN(4);
  } >ROM
  
  .init_array :
  {
    . = ALIGN(4);
    PROVIDE_HIDDEN( __init_array_start = . );
    KEEP( *(SORT(.init_array.*)) )
    KEEP( *(.init_array*) )
    PROVIDE_HIDDEN( __init_array_end = . );
    . = ALIGN(4);
  } >ROM
  
  .fini_array :
  {
    . = ALIGN(4);
    PROVIDE_HIDDEN( __fini_array_start = . );
    KEEP( *(SORT(.fini_array.*)) )
    KEEP( *(.fini_array*) )
    PROVIDE_HIDDEN( __fini_array_end = . );
    . = ALIGN(4);
    
    __etext = .;        /* define a global symbols at end of code */
  } >ROM

 /* Used by the startup to initialize data */
 	_sidata = LOADADDR(.data);

	.data : 
	{
		. = ALIGN(4);
		__data_start__ = .;
		_sdata = .;        /* create a global symbol at data start */
    	*(.data)           /* .data sections */
		*(.data*)
		*(vtable)
		. = ALIGN(4);
		/* All data end */
		__data_end__ = .;
	} >RAM AT>ROM

	.bss :
	{
		__bss_start__ = .;
		*(.bss*)
		*(COMMON)
		__bss_end__ = .;
	} >RAM
	
	.heap :
	{
		__end__ = .;
		end = __end__;
		*(.heap*)
		__HeapLimit = .;
	} > RAM

	/* .stack_dummy section doesn't contains any symbols. It is only
	 * used for linker to calculate size of stack sections, and assign
	 * values to stack symbols later */
	.stack_dummy :
	{
		*(.stack)
	} > RAM

	/* Set stack top to end of RAM, and stack limit move down by
	 * size of stack_dummy section */
	__StackTop = ORIGIN(RAM) + LENGTH(RAM);
	__StackLimit = __StackTop - SIZEOF(.stack_dummy);
	PROVIDE(__stack = __StackTop);
	
	/* Check if data + heap + stack exceeds RAM limit */
	ASSERT(__StackLimit >= __HeapLimit, "region RAM overflowed with stack")
}