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@ -76,6 +76,12 @@ forward-reference labels.
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However, they *cannot* forward-reference other constants.
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When defining a constant, if the symbol specified has already been defined, no
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error occur and the first value defined stays intact. This allows for "user
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override" of programs.
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It's also important to note that constants always override labels, regardless
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of declaration order.
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## Expressions
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@ -119,12 +125,8 @@ allowed. An included file cannot have an `.inc` directive.
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**.equ**: Binds a symbol named after the first parameter to the value of the
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expression written as the second parameter. Example:
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`.equ foo 0x42+'A'`
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`.equ foo 0x42+'A'`. See "Constants" above.
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If the symbol specified has already been defined, no error occur and
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the first value defined stays intact. This allows for "user override"
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of programs.
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**.fill**: Outputs the number of null bytes specified by its argument, an
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expression. Often used with `$` to fill our binary up to a certain
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offset. For example, if we want to place an instruction exactly at
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@ -112,11 +112,11 @@ symRegister:
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push de ; --> lvl 3
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ld d, 0
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ld e, c
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add hl, de ; if carry set here, sbc will carry too
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add hl, de ; if carry set here, sbc will carry too
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ld e, (ix+2) ; DE --> pointer to record list, which is also
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ld d, (ix+3) ; the end of names pool
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; DE --> names end
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sbc hl, de ; compares hl and de destructively
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pop de ; <-- lvl 3
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pop hl ; <-- lvl 2
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@ -192,11 +192,11 @@ _symFind:
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jr z, .end ; match! Z already set, IY and HL placed.
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.skip:
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; ok, next!
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push de ; --> lvl 1
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ld de, 0x0003
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add iy, de ; faster and shorter than three inc's
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ld e, (iy-3) ; offset is also compulsory, so no extra bytes used
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ld e, (iy-3) ; offset is also compulsory, so no extra bytes used
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; (iy-3) holds the name length of the string just processed
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add hl, de ; advance HL by (iy-3) characters
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pop de ; <-- lvl 1
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@ -219,13 +219,13 @@ symFindVal:
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push ix
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call symIsLabelLocal
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jr z, .local
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; global. Let's try labels first, then consts
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; global. Let's try consts first, then symbols
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push hl ; --> lvl 1. we'll need it again if not found.
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ld ix, SYM_GLOBAL_REGISTRY
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ld ix, SYM_CONST_REGISTRY
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call _symFind
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pop hl ; <-- lvl 1
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jr z, .found
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ld ix, SYM_CONST_REGISTRY
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ld ix, SYM_GLOBAL_REGISTRY
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call _symFind
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jr nz, .end
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.found:
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Binary file not shown.
Binary file not shown.
@ -2,8 +2,11 @@ jp test
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.inc "core.asm"
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dummyLabel:
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testNum: .db 1
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.equ dummyLabel 0x42
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test:
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ld hl, 0xffff
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ld sp, hl
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@ -30,6 +33,13 @@ test:
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jp p, fail ; negative
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call nexttest
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; Test that .equ can override label
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ld a, 0x42
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ld hl, dummyLabel
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cp l
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jp nz, fail
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call nexttest
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; *** cpHLDE ***
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ld hl, 0x42
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ld de, 0x42
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