As there is no header file for STM8, I was trying to create my own using 2
different approaches.
They each produce different -though correct- outputs.
Code Sample 1:
typedef struct
{
unsigned char PIN0:1 ;
unsigned char PIN1:1 ;
unsigned char PIN2:1 ;
unsigned char PIN3:1 ;
unsigned char PIN4:1 ;
unsigned char PIN5:1 ;
unsigned char PIN6:1 ;
unsigned char PIN7:1 ;
} _BITS_ ;
typedef union
{
_BITS_ sbits ;
unsigned char _sfrByte_ ;
} _SFR_ ;
//--------------------------------
volatile _SFR_ __at (0x500F) _PD_ODR_ ;
//---------------------------------
#define PD_ODR _PD_ODR_._sfrByte_
#define PD1 _PD_ODR_.sbits.PIN1
//---------------------------------
void main(void)
{
PD_ODR |= 1<<1 ;
PD1 = 1 ;
}
//---------------------------------
This produces (main.asm):
.globl _main
.globl __PD_ODR_
;--------------------------------------------------------
; ram data
;--------------------------------------------------------
.area DATA
__PD_ODR_ = 0x500f
...... some instructions ......
_main:
; main.c: 26: PD_ODR |= 1<<1 ;
ld a, __PD_ODR_+0
or a, #0x02
ld __PD_ODR_+0, a
; main.c: 28: PD1 = 1 ;
bset __PD_ODR_+0, #1
; main.c: 29: }
ret
========================================
Code sample 2:
#define _SFR_(mem_addr) (*(volatile unsigned char *)(0x5000 +
(mem_addr)))
/* PORT D */
#define PD_ODR _SFR_(0x0F)
void main(void)
{
PD_ODR |= 1 << 1 ;
}
//-------------------------------------------
Produces:
_main:
; main.c: 9: PD_ODR |= 1 << 1 ;
bset 20495, #1
; main.c: 10: }
ret
This does seem more efficient.
Its curious why the "PD_ODR |= 1<<1" produced the "ld a ...." in the 1st
example,
while just the 'bset ...' in the second, when both cases were absolute
addresses.
The 1st sample did produce "bset" for "PD1=1",(which is essentially
"PD_ODR = 1 <<1" ).
Best Regards,
- Royce Pereira,
T-Star Instrumentation,
102, Creative Industries,
Sunder Nagar Road # 2,
Kalina, Santacruz-East,
Mumbai- 400098,
INDIA
Cell: +91 9820061636
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