DSP编程中使用的预编译指令 #pragma(2008-12-10 10:55:09)转载▼标签：杂谈【原创】转载请注明出处**** TypeWritter: Li Hui*** Start Time: Nov.19.2008*** Version 1.3**** use word to instead 2 * 16bit short data's access ** void vecsum4(short *restrict sum, restrict short *in1, restrict short *in2, unsigned int N){int i;#pragma MUST_ITERATE(10);for(i=0;i<(N/2);i++)_amem4(&sum[i]) =add2(_amem4_const(&in1[i]),_amem4_const(&in2[i])); }** near variable's access **LDW *dp(_address),a1** far variables' access **MVKL _address,a1MVKH _address,a1LDW *a1,a0** far function call **MVKL _func,a1MVKH _func,a1B a1** default is near type **** if you use -mr1 option, all the func are 'far' if you don't use -mr1, default is 'near'if you use -mr0, then all the array or matrix are 'far', program is 'near'if you use -mr1, then all the array or matrix are 'near', program is 'far'if you use -mr2, then all the array, matrix, program are 'far'if you use -mr3, then all data and program are 'far'**** not-related **void foo(int * restrict a, int * restrict b)void foo(int c[restrict], int d[restrict])** difference of const-pointer and point to const**int * const p = &x; ** a const pointer who point to a variable named x **const int * p = &x; ** a pointer who point to a const named x, the pointer can point another variable **** volatile - to guarantee a variable can not be optimized by optimizer **unsigned int *ctrl;while(*ctrl !=0xFF)...** optimizer will treat ctrl a const **** so we should specify the ctrl's type is 'volatile' ** volatile unsigned int * ctrl;** That's ok **** Embedded the assembly language into the .C file **asm(" Assembly Language... ");** Useful Pragma Directive **** (1) CODE_SECTION **** Allocate space for symbol in the section named "section name" **#pragma CODE_SECTION(symbol,"section name"); // in C language** (2) DATA_ALIGN **** align symbol to the column edge specfied by the constant ** #pragma DATA_ALIGN(symbol,constant); // constant must be power of 2eg1:#pragma DATA_ALIGN(inputArray,8);// when you use DSPLIB FFT functions** (3) DATA_MEM_BANK **** align the symbol and variables to the page edge specified by the constant **** avoid the data's overlapped storage **#pragma DATA_MEM_BANK(symbol,constant); ** C64 : constant must be 0-15 and must be even **** (4) DATA_SECTION **** Allocate space for symbol in the section named "section name" **** 4-1 C Language **#pragma DATA_SECTION(symbol,"section name");** 4-2 C++ Language **#pragma DATA_SECTION("section name");** 4-3 Assembly Language **.global _bufferA.bss _bufferA,512,4.global _bufferB_bufferB .usect "section name",512,4** (5) FUNC_CANNOT_INLINE **** this function can not be inline, even the function is defined 'inline' **#pragma FUNC_CANNOT_INLINE(func);** (6) FUNC_EXT_CALLED **** if you add -pm options in the compile period, the compiler will erase the function which haven't beencalled by main, but acturally, the function may be called by .asm file. **#pragma FUNC_EXT_CALLED(func);** restriction: func can not be _c_int00 **** (7) FUNC_INTERRUPT_THRESHOLD **#pragma FUNC_INTERRUPT_THRESHOLD(func,threshold);eg1:#pragma FUNC_INTERRUPT_THRESHOLD(func1,2000);** the period between the func1's interrupts must lager than 2000 clock cycle **eg2:#pragma FUNC_INTERRUPT_THRESHOLD(func2,1);** the func2 can always be interrupted **eg3:#pragma FUNC_INTERRUPT_THRESHOLD(func3,-1);** the func2 can not be interrupted **** (8) FUNC_IS_PURE **** This function has no side-effect, if you do not need the value returned by func, you can delete its' callyou can delete the copy of the func**#pragma FUNC_IS_PURE(func);** (9) FUNC_IS_SYSTEM **** this function has the ANSI standard operation, the directive must be used for ANSI standard function **** for example: memcpy, strcmp and so on **#pragma FUNC_IS_SYSTEM(func);** (10) FUNC_NEVER_RETURNS **** this function never returns, so compiler can not terminate this function or free stack and so on **#pragma FUNC_NEVER_RETURNS(func);** (11) FUNC_NO_GLOBAL_ASG **** this function will not assign global variables and not contains .asm sentences **#pragma FUNC_NO_GLOBAL_ASG(func);** (12) FUNC_NO_IND_ASG **** this function will not allocate space via pointer and not contains .asm sentences **#pragma FUNC_NO_IND_ASG(func);** (13) INTERRUPT **** you can use the function to handle the DSP's interrupt ** #pragma INTERRUPT(func);** (14) MUST_ITERATE **** Specify the cycle's minimum times, maximun times and the times must be multiple of 'multiple' **#pragma MUST_ITERATE(min,max,multiple);** (15) NMI_INTERRUPT **** you can use the function to handle the Non Maskable Interrupt(NMI) **#pragma NMI_INTERRUPT(func);** (16) PROB_ITERATE **** Specify the cycle's minimum times, maximun times **#pragma PROB_ITERATE(min,max);** (17) STRUCT_ALIGN **** Like to DATA_ALIGN, using for defination of struct and class **#pragma STRUCT_ALIGN(type,constact expression);eg:typedef strct st_tag{int a;short b;}st_typedef;#pragma STRUCT_ALIGN(st_tag,128);** (18) UNROLL **** Specify which number of cycle times can not be unfolded ** #pragma UNROLL(n);。
