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delay clearing high part of literals count until we really have to in 6809 LZSA1 depacker

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This commit is contained in:
Doug Masten 2020-06-26 23:41:13 -05:00
parent 27562f4761
commit 28ca829924
1 changed files with 2 additions and 2 deletions
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4
asm/6809/unlzsa1b.s
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@ -67,7 +67,6 @@ lz1cpymt lda ,-u ; copy matched byte
lz1token ldb ,-x ; load next token into B: O|LLL|MMMM lz1token ldb ,-x ; load next token into B: O|LLL|MMMM
pshs b ; save it pshs b ; save it
clra ; clear A (high part of literals count)
andb #$70 ; isolate LLL (embedded literals count) in B andb #$70 ; isolate LLL (embedded literals count) in B
beq lz1nolt ; skip if no literals beq lz1nolt ; skip if no literals
cmpb #$70 ; LITERALS_RUN_LEN? cmpb #$70 ; LITERALS_RUN_LEN?
@ -75,7 +74,7 @@ lz1token ldb ,-x ; load next token into B: O|LLL|MMMM
ldb ,-x ; load extra literals count byte ldb ,-x ; load extra literals count byte
addb #$07 ; add LITERALS_RUN_LEN addb #$07 ; add LITERALS_RUN_LEN
bcc lz1gotlt ; if no overflow, we got the complete count, copy bcc lz1gotla ; if no overflow, we got the complete count, copy
bne lz1midlt bne lz1midlt
ldd ,--x ; load 16 bit count in D (low part in B, high in A) ldd ,--x ; load 16 bit count in D (low part in B, high in A)
@ -90,6 +89,7 @@ lz1declt lsrb ; shift literals count into place
lsrb lsrb
lsrb lsrb
lz1gotla clra ; clear A (high part of literals count)
lz1gotlt tfr x,u lz1gotlt tfr x,u
tfr d,x ; transfer 16-bit count into X tfr d,x ; transfer 16-bit count into X
lz1cpylt lda ,-u ; copy literal byte lz1cpylt lda ,-u ; copy literal byte