A.1.2 Changing allocated section
The default allocation sections are as follows:
- | Variables with no initial value: .bss section |
- | Variables with initial value: .data section |
- | const constants: .const section |
To change the allocated section, specify the attribute strings using #pragma section directive.
The relationship between attribute strings and the section generated is as follows.
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r0_disp16
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Yes
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.zdata
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Possible
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r0
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ld/st 1 instruction
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No
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.zbss
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Possible
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r0
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ld/st 1 instruction
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r0_disp23
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Yes
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.zdata23
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Possible
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r0
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ld23/st23 1 instruction
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No
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.zbss23
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Possible
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r0
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ld23/st23 1 instruction
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r0_disp32
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Yes
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.data
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Possible
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r0
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movhi+ld/st 2 instruction
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No
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.bss
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Possible
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r0
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movhi+ld/st 2 instruction
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ep_auto
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Yes/No
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Automatically selected from among .tdata4, .tdata5, .tdata7, and .tdata8
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Impossible
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ep
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sld/sst 1 instruction
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ep_disp4
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Yes
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.tdata4
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Possible
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ep
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sld/sst 1 instruction
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No
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.tbss4
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Possible
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ep
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sld/sst 1 instruction
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ep_disp5
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Yes
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.tdata5
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Possible
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ep
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sld/sst 1 instruction
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No
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.tbss5
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Possible
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ep
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sld/sst 1 instruction
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ep_disp7
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Yes
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.tdata7
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Possible
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ep
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sld/sst 1 instruction
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No
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.tbss7
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Possible
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ep
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sld/sst 1 instruction
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ep_disp8
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Yes
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.tdata8
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Possible
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ep
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sld/sst 1 instruction
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No
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.tbss8
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Possible
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ep
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sld/sst 1 instruction
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ep_disp16
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Yes
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.edata
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Possible
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ep
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ld/st 1 instruction
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No
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.ebss
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Possible
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ep
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ld/st 1 instruction
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ep_disp23
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Yes
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.edata23
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Possible
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ep
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ld23/st23 1 instruction
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No
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.ebss23
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Possible
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ep
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ld23/st23 1 instruction
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gp_disp16
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Yes
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.sdata
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Possible
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gp
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ld/st 1 instruction
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No
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.sbss
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Possible
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gp
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ld/st 1 instruction
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gp_disp23
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Yes
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.sdata23
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Possible
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gp
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ld23/st23 1 instruction
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No
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.sbss23
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Possible
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gp
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ld23/st23 1 instruction
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const
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Yes
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.const
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Possible
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r0
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movhi+ld/st 2 instruction
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zconst
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Yes
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.zconst
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Possible
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r0
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ld/st 1 instruction
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zconst23
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Yes
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.zconst23
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Possible
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r0
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ld23/st23 1 instruction
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default
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After this statement, any previous #pragma section will be ignored, and the default allocation will be used.
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Example | #pragma section directive description |
#pragma section gp_disp16 "mysdata"
int a = 1; /*allocated to mysdata.sdata attribute section*/
int b; /*allocated to mysdata.sbss attribute section*/
#pragma section default
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When referencing a variable using the #pragma section directive from a function in another file (i.e. reference file), it is necessary to also specify the #pragma section directive in the reference file and to define the affected variable as extern format.
Unlike when specifying a variable by means of a definition or declaration, it outputs the following error if the variable cannot be accessed with the specified section attribute.
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E0562330 : Relocation size overflow : "file"-"section"-"offset"
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Example 1. | File that defines a table |
#pragma section zconst
const unsigned char table_data[9] = {1, 2, 3, 4, 5, 6, 7, 8, 9}; /*allocated to .zconst section*/
#pragma section default
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Example 2. | File that references a table |
#pragma section zconst
extern const unsigned char table_data[]; /*allocated to .zconst section*/
#pragma section default
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Code such as the following can be used if portability of C source to the SH family of compilers is a concern.
Example | #pragma section directive description |
#pragma section mydata
int a = 1; /*allocated to mydata.data section*/
int b; /*allocated to mydata.bss section*/
#pragma section default
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