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47 lines
1.1 KiB
ArmAsm
47 lines
1.1 KiB
ArmAsm
;
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; Ullrich von Bassewitz, 2005-04-21
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;
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; char* __fastcall__ getenv (const char* name);
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;
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; Beware: putenv() knows about zero page usage in this module!
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;
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.export _getenv
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.import __environ, __envcount
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.import searchenv
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.import return0
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.import ptr1:zp, ptr3:zp, tmp1:zp
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.code
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;----------------------------------------------------------------------------
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; getenv()
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.proc _getenv
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sta ptr1
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stx ptr1+1 ; Save name
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; Search for the string in the environment. searchenv will set the N flag if
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; the string is not found, otherwise X contains the index of the entry, ptr3
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; contains the entry and Y the offset of the '=' in the string.
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jsr searchenv
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bpl found
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jmp return0 ; Not found, return NULL
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; Found the entry. Calculate the pointer to the right side of the environment
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; variable. Because we want to skip the '=', we will set the carry.
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found: ldx ptr3+1 ; High byte of result
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tya
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sec
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adc ptr3
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bcc @L9
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inx
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@L9: rts
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.endproc
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