1                      Microsoft's Azure RTOS ThreadX for Cortex-M23
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3                                   Using the GNU Tools
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5
61.  Building the ThreadX run-time Library
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8An example .bat file is in the example_build directory.
9Files tx_thread_stack_error_handler.c and tx_thread_stack_error_notify.c
10replace the common files of the same name.
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122.  Demonstration System
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14No demonstration example is provided.
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173.  System Initialization
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19The entry point in ThreadX for the Cortex-M23 using gnu tools uses the standard GNU
20Cortex-M23 reset sequence. From the reset vector the C runtime will be initialized.
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22The ThreadX tx_initialize_low_level.S file is responsible for setting up
23various system data structures, the vector area, and a periodic timer interrupt
24source.
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26In addition, _tx_initialize_low_level determines the first available
27address for use by the application, which is supplied as the sole input
28parameter to your application definition function, tx_application_define.
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314.  Register Usage and Stack Frames
32
33The following defines the saved context stack frames for context switches
34that occur as a result of interrupt handling or from thread-level API calls.
35All suspended threads have the same stack frame in the Cortex-M23 version of
36ThreadX. The top of the suspended thread's stack is pointed to by
37tx_thread_stack_ptr in the associated thread control block TX_THREAD.
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39
40  Stack Offset     Stack Contents
41
42     0x00               LR          Interrupted LR (LR at time of PENDSV)
43     0x04               r8
44     0x08               r9
45     0x0C               r10
46     0x10               r11
47     0x14               r4
48     0x18               r5
49     0x1C               r6
50     0x20               r7
51     0x24               r0          (Hardware stack starts here!!)
52     0x28               r1
53     0x2C               r2
54     0x30               r3
55     0x34               r12
56     0x38               lr
57     0x3C               pc
58     0x40               xPSR
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615.  Improving Performance
62
63To make ThreadX and the application(s) run faster, you can enable
64all compiler optimizations.
65
66In addition, you can eliminate the ThreadX basic API error checking by
67compiling your application code with the symbol TX_DISABLE_ERROR_CHECKING
68defined.
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716.  Interrupt Handling
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73ThreadX provides complete and high-performance interrupt handling for Cortex-M23
74targets. There are a certain set of requirements that are defined in the
75following sub-sections:
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77
786.1  Vector Area
79
80The Cortex-M23 vectors start at the label __tx_vectors or similar. The application may modify
81the vector area according to its needs. There is code in tx_initialize_low_level() that will
82configure the vector base register.
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84
856.2 Managed Interrupts
86
87ISRs can be written completely in C (or assembly language) without any calls to
88_tx_thread_context_save or _tx_thread_context_restore. These ISRs are allowed access to the
89ThreadX API that is available to ISRs.
90
91ISRs written in C will take the form (where "your_C_isr" is an entry in the vector table):
92
93void    your_C_isr(void)
94{
95
96    /* ISR processing goes here, including any needed function calls.  */
97}
98
99ISRs written in assembly language will take the form:
100
101
102    .global  your_assembly_isr
103    .thumb_func
104your_assembly_isr:
105; VOID your_assembly_isr(VOID)
106; {
107        PUSH    {r0, lr}
108;
109;    /* Do interrupt handler work here */
110;    /* BL <your interrupt routine in C> */
111
112        POP     {r0, r1}
113        MOV     lr, r1
114        BX      lr
115; }
116
117
118Note: the Cortex-M23 requires exception handlers to be thumb labels, this implies bit 0 set.
119To accomplish this, the declaration of the label has to be preceded by the assembler directive
120.thumb_func to instruct the linker to create thumb labels. The label __tx_IntHandler needs to
121be inserted in the correct location in the interrupt vector table. This table is typically
122located in either your runtime startup file or in the tx_initialize_low_level.S file.
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1257.  Revision History
126
127For generic code revision information, please refer to the readme_threadx_generic.txt
128file, which is included in your distribution. The following details the revision
129information associated with this specific port of ThreadX:
130
13106-02-2021  Release 6.1.7 changes:
132            tx_thread_secure_stack_initialize.S New file
133            tx_thread_schedule.S                Added secure stack initialize to SVC hander
134            tx_thread_secure_stack.c            Fixed stack pointer save, initialize in handler mode
135
13604-02-2021  Release 6.1.6 changes:
137            tx_port.h                           Updated macro definition
138            tx_thread_schedule.s                Added low power support
139
14003-02-2021  The following files were changed/added for version 6.1.5:
141            tx_port.h                       Added ULONG64_DEFINED
142
14312-31-2020  The following files were
144            changed/added for port specific version 6.1.3:
145
146            tx_port.h                       Remove unneeded include files,
147                                            use builtin functions,
148                                            modified comments.
149
150            tx_thread_secure_stack.c        Remove unneeded include file,
151                                            use inline get/set functions,
152                                            modified comments.
153
15409-30-2020  Initial ThreadX 6.1 version for Cortex-M23 using GNU tools.
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156
157Copyright(c) 1996-2020 Microsoft Corporation
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159
160https://azure.com/rtos
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