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Literal evaluation messed up

Greg Toombs

When I write the following in uVision,

mov A, -2000

I want A to contain 0x30, as -2000 is 0xF830. Instead it contains 0x05. Is there any predefined macro to be able to treat a literal as sixteen bits and extract the lower (or upper) eight bits out of it?

Thanks.

Parents
  • 0 in reply to Greg Toombs

    Actually it does make sense to cram -2000 into TL registers
    sure, but then why do you post mov a,...

    anyhow
    this

    #define NEG_VAL -2000
#define POS_VAL 2000


           mov   a,#LOW (NEG_VAL)
           mov   a,#HIGH (NEG_VAL)
           mov   a,#LOW (-POS_VAL)
           mov   a,#HIGH (-POS_VAL)
           mov   a,#LOW (-2000)
           mov   a,#HIGH (-2000)

    Gives

    0092 7430            607                mov   a,#LOW (-2000)
0094 74F8            608                mov   a,#HIGH (-2000)
0096 7430            609                mov   a,#LOW (-2000)
0098 74F8            610                mov   a,#HIGH (-2000)
009A 7430            611                mov   a,#LOW (-2000)
009C 74F8            612                mov   a,#HIGH (-2000)


    what is the problem? I guess that like so many others (including myself) you are periodically blind to a missing '#' Erik

Reply
  • 0 in reply to Greg Toombs

    Actually it does make sense to cram -2000 into TL registers
    sure, but then why do you post mov a,...

    anyhow
    this

    #define NEG_VAL -2000
#define POS_VAL 2000


           mov   a,#LOW (NEG_VAL)
           mov   a,#HIGH (NEG_VAL)
           mov   a,#LOW (-POS_VAL)
           mov   a,#HIGH (-POS_VAL)
           mov   a,#LOW (-2000)
           mov   a,#HIGH (-2000)

    Gives

    0092 7430            607                mov   a,#LOW (-2000)
0094 74F8            608                mov   a,#HIGH (-2000)
0096 7430            609                mov   a,#LOW (-2000)
0098 74F8            610                mov   a,#HIGH (-2000)
009A 7430            611                mov   a,#LOW (-2000)
009C 74F8            612                mov   a,#HIGH (-2000)


    what is the problem? I guess that like so many others (including myself) you are periodically blind to a missing '#' Erik

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