tms320f28379d fix init (#6343)

解决 tms320f28379d bsp 启动的问题。主要改动如下。

修正context.s中汇编代码错误。在旧版的代码中，操作数为32位而汇编命令却使用了针对16位数据的命令MOV，导致程序在某些情况无法正常启动线程。
由于C28x的平台下，SP只支持16bit寻址，所以用于线程空间存放的heap以及ebss段都需要放在低16位的空间，针对这个问题修改了CMD文件。此外还增加基于CMD文件基于RAM的支持，方便调试。
新增rtdef.h中RT_SECTION，RT_USED，ALIGN和RT_WEAK的定义。旧版bsp中这些定义为空，导致INIT_EXPORT注册的函数失效。
修改程序启动代码，在程序入口直接调用原生启动代码
以上改动在LAUNCHXL-F28379D 通过了测试。

2 files changed, 63 insertions, 105 deletions

diff --git a/libcpu/ti-dsp/c28x/context.s b/libcpu/ti-dsp/c28x/context.s
index 2b019e0714..297b3b2119 100644
--- a/libcpu/ti-dsp/c28x/context.s
+++ b/libcpu/ti-dsp/c28x/context.s
@@ -10,6 +10,7 @@
 ; 2019-07-03     zhaoxiaowei  add _rt_hw_calc_csb function to support __rt_ffs.
 ; 2019-12-05     xiaolifan    add support for hardware fpu32
 ; 2022-06-21     guyunjie     trim pendsv (RTOSINT_Handler)
+; 2022-08-24     guyunjie     fix bugs in context switching
 
     .ref   _rt_interrupt_to_thread
     .ref   _rt_interrupt_from_thread
@@ -39,7 +40,6 @@
 
 RT_CTX_SAVE  .macro
 
-
     PUSH    AR1H:AR0H
     PUSH    XAR2
     PUSH    XAR3
@@ -90,7 +90,6 @@ RT_CTX_RESTORE  .macro
     POP     XAR3
     POP     XAR2
 
-
     MOVZ    AR0 , @SP
     SUBB    XAR0, #6
     MOVL    ACC , *XAR0
@@ -98,7 +97,6 @@ RT_CTX_RESTORE  .macro
     MOV     AL, IER
     MOVL   *XAR0, ACC
 
-
     POP     AR1H:AR0H
 
     .endm
@@ -130,23 +128,19 @@ _rt_hw_interrupt_enable:
 
 ;
 ; void rt_hw_context_switch(rt_uint32 from, rt_uint32 to);
-; r0 --> from
-; r4 --> to
-
-
+; ACC   --> from
+; SP[4] --> to
+;
     .asmfunc
 _rt_hw_context_switch_interrupt:
-    MOVL    XAR0, #0
-    MOV     AR0, AL
+    MOVL    XAR0, ACC
     MOVL    XAR4, *-SP[4]
     ; set rt_thread_switch_interrupt_flag to 1
     MOVL    XAR5, #_rt_thread_switch_interrupt_flag
-    MOVL    XAR6, *XAR5
-    MOVL    ACC, XAR6
-    CMPB    AL, #1
-    B       _reswitch, EQ
-    MOVL     XAR6, #1
-    MOVL    *XAR5, XAR6
+    MOVL    ACC, *XAR5
+    BF      _reswitch, NEQ                     ; ACC!=0
+    MOVB    ACC, #1
+    MOVL    *XAR5, ACC
 
     MOVL    XAR5, #_rt_interrupt_from_thread   ; set rt_interrupt_from_thread
     MOVL    *XAR5, XAR0
@@ -160,23 +154,19 @@ _reswitch:
 
 ;
 ; void rt_hw_context_switch(rt_uint32 from, rt_uint32 to);
-; r0 --> from
-; r4 --> to
-
-
+; ACC   --> from
+; SP[4] --> to
+;
     .asmfunc
 _rt_hw_context_switch:
-    MOVL    XAR0, #0
-    MOV     AR0, AL
+    MOVL    XAR0, ACC
     MOVL    XAR4, *-SP[4]
     ; set rt_thread_switch_interrupt_flag to 1
     MOVL    XAR5, #_rt_thread_switch_interrupt_flag
-    MOVL    XAR6, *XAR5
-    MOVL    ACC, XAR6
-    CMPB    AL, #1
-    B       _reswitch2, EQ
-    MOVL     XAR6, #1
-    MOVL    *XAR5, XAR6
+    MOVL    ACC, *XAR5
+    BF      _reswitch2, NEQ                    ; ACC!=0
+    MOVB    ACC, #1
+    MOVL    *XAR5, ACC
 
     MOVL    XAR5, #_rt_interrupt_from_thread   ; set rt_interrupt_from_thread
     MOVL    *XAR5, XAR0
@@ -189,63 +179,64 @@ _reswitch2:
     LRETR
     .endasmfunc
 
-     .asmfunc
+;
+; * void rt_hw_context_switch_to(rt_uint32 to);
+; * ACC --> to
+;
+    .asmfunc
+_rt_hw_context_switch_to:
+    ; get to thread
+    MOVL    XAR1, #_rt_interrupt_to_thread
+    MOVL    *XAR1, ACC
+
+    ; set from thread to 0
+    MOVL    XAR1, #_rt_interrupt_from_thread
+    MOVL    XAR0, #0
+    MOVL    *XAR1, XAR0
+
+    ; set interrupt flag to 1
+    MOVL    XAR1, #_rt_thread_switch_interrupt_flag
+    MOVL    XAR0, #1
+    MOVL    *XAR1, XAR0
+
+    TRAP    #16
+
+    ; never reach here!
+    .endasmfunc
+
+    .asmfunc
 _RTOSINT_Handler:
     ; disable interrupt to protect context switch
     ; DINT ;this is done by hardware so not needed
 
     ; get rt_thread_switch_interrupt_flag
-    MOV     AR0, #_rt_thread_switch_interrupt_flag
-    MOV     AL, *AR0
-    MOV     AR1, AL
-    CMP     AR1, #0
-    B       rtosint_exit, EQ         ; pendsv already handled
+    MOVL    XAR0, #_rt_thread_switch_interrupt_flag
+    MOVL    ACC, *XAR0
+    BF      rtosint_exit, EQ         ; pendsv already handled
 
     ; clear rt_thread_switch_interrupt_flag to 0
-    MOV     AR1, #0x00
-    MOV     *AR0, AR1
-
-    MOV     AR0, #_rt_interrupt_from_thread
-    MOV     AL, *AR0
-    MOV     AR1, AL
-    CMP     AR1, #0
-    B       switch_to_thread, EQ    ; skip register save at the first time
-
-;#if defined (__VFP_FP__) && !defined(__SOFTFP__)
-;    TST     lr, #0x10           ; if(!EXC_RETURN[4])
-;    VSTMDBEQ r1!, {d8 - d15}    ; push FPU register s16~s31
-;#endif
+    MOVL    XAR1, #0
+    MOVL    *XAR0, XAR1
 
-    RT_CTX_SAVE     ; push r4 - r11 register
+    MOVL    XAR0, #_rt_interrupt_from_thread
+    MOVL    ACC, *XAR0
+    BF      switch_to_thread, EQ     ; skip register save at the first time
 
-;#if defined (__VFP_FP__) && !defined(__SOFTFP__)
-;    MOV     r4, #0x00           ; flag = 0
+    RT_CTX_SAVE                      ; push cpu registers
 
-;    TST     lr, #0x10           ; if(!EXC_RETURN[4])
-;    MOVEQ   r4, #0x01           ; flag = 1
-
-;    STMFD   r1!, {r4}           ; push flag
-;#endif
-
-    MOV     AL, *AR0
-    MOV     AR0, AL
+    MOVL    ACC, *XAR0
+    MOVL    XAR0, ACC
     MOVZ    AR1, @SP                 ; get from thread stack pointer
-    MOV     *AR0, AR1                ; update from thread stack pointer
+    MOVL    *XAR0, XAR1              ; update from thread stack pointer
 
 switch_to_thread:
-    MOV     AR1, #_rt_interrupt_to_thread
-    MOV     AL, *AR1
-    MOV     AR1, AL
-    MOV     AL, *AR1
-    MOV     AR1, AL                ; load thread stack pointer
-
-;#if defined (__VFP_FP__) && !defined(__SOFTFP__)
-;    LDMFD   r1!, {r3}           ; pop flag
-;#endif
+    MOVL    XAR1, #_rt_interrupt_to_thread
+    MOVL    ACC, *XAR1
+    MOVL    XAR1, ACC
+    MOVL    ACC, *XAR1
+    MOV     @SP, AL                  ; load thread stack pointer
 
-    MOV     @SP, AR1
-
-    RT_CTX_RESTORE     ; pop r4 - r11 register
+    RT_CTX_RESTORE                   ; pop cpu registers
 
 rtosint_exit:
     ; do not restore interrupt here: to be restored according to the
@@ -287,38 +278,6 @@ _rt_hw_calc_csb:
     lretr
     .endasmfunc
 
-;
-; * void rt_hw_context_switch_to(rt_uint32 to);
-; * r0 --> to
-
-    .asmfunc
-_rt_hw_context_switch_to:
-    MOV     AR1, #_rt_interrupt_to_thread
-    MOV     *AR1, AL
-
-;#if defined (__VFP_FP__) && !defined(__SOFTFP__)
-    ; CLEAR CONTROL.FPCA
-;    MRS     r2, CONTROL         ; read
-;    BIC     r2, #0x04           ; modify
-;    MSR     CONTROL, r2         ; write-back
-;#endif
-
-    ; set from thread to 0
-    MOV     AR1, #_rt_interrupt_from_thread
-    MOV     AR0, #0x0
-    MOV     *AR1, AR0
-
-    ; set interrupt flag to 1
-    MOV     AR1, #_rt_thread_switch_interrupt_flag
-    MOV     AR0, #1
-    MOV     *AR1, AR0
-
-    TRAP    #16
-
-
-    ; never reach here!
-    .endasmfunc
-
 ; compatible with old version
     .asmfunc
 _rt_hw_interrupt_thread_switch:
diff --git a/libcpu/ti-dsp/c28x/cpuport.c b/libcpu/ti-dsp/c28x/cpuport.c
index 8903ea0a40..9ffd96d4f7 100644
--- a/libcpu/ti-dsp/c28x/cpuport.c
+++ b/libcpu/ti-dsp/c28x/cpuport.c
@@ -76,9 +76,8 @@ rt_uint8_t *rt_hw_stack_init(void       *tentry,
     unsigned long       i;
 
     stk  = stack_addr;
-    stk  = (rt_uint8_t *)RT_ALIGN((rt_uint32_t)stk, 8);
-    //stk -= sizeof(struct stack_frame);
-    stk += 1;
+    stk  = (rt_uint8_t *)RT_ALIGN((rt_uint32_t)stk, 2);
+    stk += 1; /*to work around the stack alignment*/
 
     stack_frame = (struct stack_frame *)stk;