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mtei/avr-gcc_PROGMEM.md

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avr-gcc PROGMEM tips
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avr-gcc_PROGMEM.md

avr-gcc PROGMEM tips

//avr-gcc -mmcu=atmega32u4 -S -O2 -o - progtest1.c
#include <avr/pgmspace.h>
const char a = 100;
% avr-gcc -mmcu=atmega32u4 -O2 -S -o - vartest1.c
	.file	"vartest1.c"
__SP_H__ = 0x3e
__SP_L__ = 0x3d
__SREG__ = 0x3f
__tmp_reg__ = 0
__zero_reg__ = 1
	.text
.global	a
	.section	.rodata
	.type	a, @object
	.size	a, 1
a:
	.byte	100
	.ident	"GCC: (Homebrew AVR GCC 8.4.0_2) 8.4.0"
.global __do_copy_data
//avr-gcc -mmcu=atmega32u4 -S -O2 -o - progtest2.c
#include <avr/pgmspace.h>
const char b PROGMEM = 101;
% avr-gcc -mmcu=atmega32u4 -O2 -S -o - vartest2.c
	.file	"vartest2.c"
__SP_H__ = 0x3e
__SP_L__ = 0x3d
__SREG__ = 0x3f
__tmp_reg__ = 0
__zero_reg__ = 1
	.text
.global	b
	.section	.progmem.data,"a",@progbits
	.type	b, @object
	.size	b, 1
b:
	.byte	101
	.ident	"GCC: (Homebrew AVR GCC 8.4.0_2) 8.4.0"
<avr/pgmspace.h>
#define __ATTR_PROGMEM__ __attribute__((__progmem__))
#define PROGMEM __ATTR_PROGMEM__
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