I am not sure I understand how the free RAM area is calculated. Can someone shed light on this? I tried different calculations and it does not add up. Look at the length of the free RAM area: 32513. Where does this number come from? Thanks.
/* ****************************************************************************************************** */
/* demo2148_blink_flash.cmd LINKER SCRIPT */
/* */
/* */
/* The Linker Script defines how the code and data emitted by the GNU C compiler and assembler are */
/* to be loaded into memory (code goes into FLASH, variables go into RAM). */
/* */
/* Any symbols defined in the Linker Script are automatically global and available to the rest of the */
/* program. */
/* */
/* To force the linker to use this LINKER SCRIPT, just add the -T demo2148_blink_flash.cmd directive */
/* to the linker flags in the makefile. */
/* */
/* LFLAGS = -Map main.map -nostartfiles -T demo2148_blink_flash.cmd */
/* */
/* */
/* The Philips boot loader supports the ISP (In System Programming) via the serial port and the IAP */
/* (In Application Programming) for flash programming from within your application. */
/* */
/* The boot loader uses RAM memory and we MUST NOT load variables or code in these areas. */
/* */
/* RAM used by boot loader: 0x40000120 - 0x400001FF (223 bytes) for ISP variables */
/* 0x40007FE0 - 0x4000FFFF (32 bytes) for ISP and IAP variables */
/* 0x40007EE0 - 0x40007FE0 (256 bytes) stack for ISP and IAP */
/* */
/* */
/* MEMORY MAP */
/* | |0x40008000 */
/* .-------->|---------------------------------| */
/* . | variables and stack |0x40007FFF */
/* ram_isp_high | for Philips boot loader | */
/* . | 32 + 256 = 288 bytes | */
/* . | | */
/* . | Do not put anything here |0x40007EE0 */
/* .-------->|---------------------------------| */
/* | UDF Stack 4 bytes |0x40007EDC <---------- _stack_end */
/* .-------->|---------------------------------| */
/* | ABT Stack 4 bytes |0x40007ED8 */
/* .-------->|---------------------------------| */
/* | FIQ Stack 4 bytes |0x40007ED4 */
/* .-------->|---------------------------------| */
/* | IRQ Stack 4 bytes |0x40007ED0 */
/* .-------->|---------------------------------| */
/* | SVC Stack 4 bytes |0x40007ECC */
/* .-------->|---------------------------------| */
/* . | |0x40007EC8 */
/* . | stack area for user program | */
/* . | | | */
/* . | | | */
/* . | | | */
/* . | V | */
/* . | | */
/* . | | */
/* . | | */
/* . | free ram | */
/* ram | | */
/* . | | */
/* . | | */
/* . |…|0x40000234 <---------- _bss_end */
/* . | | */
/* . | .bss uninitialized variables | */
/* . |…|0x40000218 <---------- _bss_start, _edata */
/* . | | */
/* . | .data initialized variables | */
/* . | |0x40000200 <---------- _data */
/* .-------->|---------------------------------| */
/* . | variables used by |0x400001FF */
/* ram_isp_low | Philips boot loader | */
/* . | 223 bytes |0x40000120 */
/* .-------->|---------------------------------| */
/* . | |0x4000011F */
/* ram_vectors | free ram | */
/* . |---------------------------------|0x40000040 */
/* . | |0x4000003F */
/* . | Interrupt Vectors (re-mapped) | */
/* . | 64 bytes |0x40000000 */
/* .-------->|---------------------------------| */
/* | | */
/* */
/* */
/* */
/* | | */
/* .--------> |---------------------------------| */
/* . | |0x0001FFFF */
/* . | | */
/* . | | */
/* . | | */
/* . | | */
/* . | | */
/* . | unused flash eprom | */
/* . | | */
/* . |…|0x0000032c */
/* . | | */
/* . | copy of .data area | */
/* flash | | */
/* . |---------------------------------|0x00000314 <----------- _etext */
/* . | | */
/* . | |0x00000180 main */
/* . | |0x00000278 feed */
/* . | main() |0x000002c4 FIQ_Routine */
/* . | |0x000002d8 SWI_Routine */
/* . | |0x000002ec UNDEF_Routine */
/* . | |0x000002b0 IRQ_routine */
/* . |---------------------------------|0x000001cc initialize */
/* . | |0x000000D4 */
/* . | Startup Code | */
/* . | (assembler) | */
/* . | | */
/* . |---------------------------------|0x00000040 Reset_Handler */
/* . | |0x0000003F */
/* . | Interrupt Vector Table (unused) | */
/* . | 64 bytes | */
/* .--------->|---------------------------------|0x00000000 _startup *
/* */
/* */
/* The easy way to prevent the linker from loading anything into a memory area is to define */
/* a MEMORY region for it and then avoid assigning any .text, .data or .bss sections into it. */
/* */
/* */
/* MEMORY */
/* { */
/* ram_isp_low(A) : ORIGIN = 0x40000120, LENGTH = 223 */
/* */
/* } */
/* */
/* */
/* Author: James P. Lynch */
/* */
/* ****************************************************************************************************** */
/* identify the Entry Point */
ENTRY(_startup)
/* specify the LPC2148 memory areas */
MEMORY
{
flash : ORIGIN = 0, LENGTH = 512K /* FLASH ROM */
ram_isp_low(A) : ORIGIN = 0x40000120, LENGTH = 223 /* variables used by Philips ISP bootloader */
ram : ORIGIN = 0x40000200, LENGTH = 32513 /* free RAM area */
ram_isp_high(A) : ORIGIN = 0x40007FE0, LENGTH = 32 /* variables used by Philips ISP bootloader */
ram_usb_dma : ORIGIN = 0x7FD00000, LENGTH = 8192 /* on-chip USB DMA RAM area (not used) */
}