zasm: allow duplicate const definition

This will allow interesting override scenarios, adding flexibility.
This commit is contained in:
Virgil Dupras 2019-07-23 16:01:23 -04:00
parent ffa28195b1
commit c2d84563dd
6 changed files with 18 additions and 1 deletions

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@ -116,6 +116,10 @@ allowed. An included file cannot have an `#inc` directive.
expression written as the second parameter. Example:
`.equ foo 0x42+'A'`
If the symbol specified has already been defined, no error occur and
the first value defined stays intact. This allows for "user override"
of programs.
**.fill**: Outputs the number of null bytes specified by its argument, an
expression. Often used with `$` to fill our binary up to a certain
offset. For example, if we want to place an instruction exactly at

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@ -149,6 +149,13 @@ handleEQU:
ld hl, DIREC_SCRATCHPAD
push ix \ pop de
call symRegisterConst ; A and Z set
jr z, .end ; success
; register ended up in error. We need to figure which error. If it's
; a duplicate error, we ignore it and return success because, as per
; ".equ" policy, it's fine to define the same const twice. The first
; value has precedence.
cp ERR_DUPSYM
; whatever the value of Z, it's the good one, return
jr .end
.badfmt:
ld a, ERR_BAD_FMT

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@ -55,5 +55,5 @@ chkerr "#inc foo" 19
chkerr "ld a, 0x100" 20
chkerr ".db 0x100" 20
chkerr "#inc \"doesnotexist\"" 21
chkerr ".equ foo 42 \\ .equ foo 42" 22
chkerr "foo:\\foo:" 22
chkoom

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@ -0,0 +1,5 @@
; It's fine to declare the same constant twice. Only the first value is
; kept
.equ FOO 42
.equ FOO 22
ld a, FOO

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@ -0,0 +1 @@
>*