8.1.12 Higher Order Byte / Higher Order Word

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8.1.12 Higher Order Byte / Higher Order Word

It is also frequently required to obtain a higher order byte or word of a larger integral type (long, int or short types). SDCC recognizes the following expressions to yield the higher order byte or word and generates optimized code for it, e.g.:

> `unsigned int gint;`
> `unsigned long int glong;`
> `foo () {`
> `unsigned char hob1, hob2;`
> `unsigned int how1, how2;`
> `...`
> `hob1 = (gint >> 8) & 0xFF;`
> `hob2 = glong >> 24;`
> `how1 = (glong >> 16) & 0xFFFF;`
> `how2 = glong >> 8;`
> `..`
> `}`

will generate the following code:

> `91 ; hob.c 15`
> `0037 85*01*06 92 mov _foo_hob1_1_1,(_gint + 1)`
> `93 ; hob.c 16`
> `003A 85*05*07 94 mov _foo_hob2_1_1,(_glong + 3)`
> `95 ; hob.c 17`
> `003D 85*04*08 96 mov _foo_how1_1_1,(_glong + 2)`
> `0040 85*05*09 97 mov (_foo_how1_1_1 + 1),(_glong + 3)`
> `0043 85*03*0A 98 mov _foo_how2_1_1,(_glong + 1)`
> `0046 85*04*0B 99 mov (_foo_how2_1_1 + 1),(_glong + 2)`

Again, variations of these cases may not be recognized. They are standard C expressions, so I heartily recommend these be the only way to get the higher order byte/word, (it is portable). Of course it will be recognized even if it is embedded in other expressions, e.g.:

> `xyz = gint + ((gint >> 8) & 0xFF);`

will still be recognized.

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