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Inconsistent warnings about different data types ?

C51 COMPILER V9.53.0.0
LX51 LINKER/LOCATER V4.66.30.0

I have the following (relevant) lines of code:

extern xdata uint8_t rtu_rx_buf[];
extern xdata uint8_t rtu_tx_buf[];
.
.
.
struct{
    uint8_t func;
    uint16_t start;
    uint16_t qty;
    uint8_t  n;
}xdata *p = &rtu_rx_buf[1];
.
.
.
p = rtu_tx_buf;
.
.
.

The first assignment to 'p' doesn't raise any complaints from the compiler or linker. The second, however, gives me the following warnings:

*** WARNING C182 IN LINE 98 OF C:\blahblahblah.c: pointer to different objects
*** WARNING L25: DATA TYPES DIFFERENT

I'm pretty sure I don't see the difference; am I missing something here?

Parents

0 Clark Leach over 9 years ago

The plot thickens... If I do this instead, I get complaints about both assignments:

struct{
    uint8_t func;
    uint16_t start;
    uint16_t qty;
    uint8_t  n;
}xdata *p;
.
.
p = &rtu_rx_buf[1];
.
.
.
p = rtu_tx_buf;
.
.
.

Maybe something else I'm doing is offending it in a much more subtle way. To put things into context a little better, this code is within a case of a switch statement thusly:

case MB_FUNC_WRITE_MULTIPLE_REGISTERS:
    {
    struct{
        uint8_t func;
        uint16_t start;
        uint16_t qty;
        uint8_t  n;
    }xdata *p = &rtu_rx_buf[1];
    uint16_t st = p->start;
    uint16_t q = p->qty;
    uint8_t n = p->n;
    uint8_t i;
    uint8_t data *dest;
    uint8_t xdata *src;

    if(blahblahblah){
        .
        .
        .
        p = rtu_tx_buf;
        .
        .
        .
    }

    }
    break;

Reply

0 Clark Leach over 9 years ago

The plot thickens... If I do this instead, I get complaints about both assignments:

struct{
    uint8_t func;
    uint16_t start;
    uint16_t qty;
    uint8_t  n;
}xdata *p;
.
.
p = &rtu_rx_buf[1];
.
.
.
p = rtu_tx_buf;
.
.
.

Maybe something else I'm doing is offending it in a much more subtle way. To put things into context a little better, this code is within a case of a switch statement thusly:

case MB_FUNC_WRITE_MULTIPLE_REGISTERS:
    {
    struct{
        uint8_t func;
        uint16_t start;
        uint16_t qty;
        uint8_t  n;
    }xdata *p = &rtu_rx_buf[1];
    uint16_t st = p->start;
    uint16_t q = p->qty;
    uint8_t n = p->n;
    uint8_t i;
    uint8_t data *dest;
    uint8_t xdata *src;

    if(blahblahblah){
        .
        .
        .
        p = rtu_tx_buf;
        .
        .
        .
    }

    }
    break;

Children

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