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authorDimitri Sokolyuk <demon@dim13.org>2017-08-19 12:15:28 +0200
committerDimitri Sokolyuk <demon@dim13.org>2017-08-19 12:15:28 +0200
commit67d25d837ac55f28a366c0a3b262e439a6e75fc3 (patch)
treedf7715c7724c5935ab87c807f3b8b4ef529315e3 /amforth-6.5/avr8/words/fetch.asm
parente0d6784e89dba33226c0edb815bb974486fa7c48 (diff)
Add AmForth
Diffstat (limited to 'amforth-6.5/avr8/words/fetch.asm')
-rw-r--r--amforth-6.5/avr8/words/fetch.asm33
1 files changed, 33 insertions, 0 deletions
diff --git a/amforth-6.5/avr8/words/fetch.asm b/amforth-6.5/avr8/words/fetch.asm
new file mode 100644
index 0000000..6cd2f2b
--- /dev/null
+++ b/amforth-6.5/avr8/words/fetch.asm
@@ -0,0 +1,33 @@
+; ( a-addr -- n )
+; Memory
+; read 1 cell from RAM address
+VE_FETCH:
+ .dw $ff01
+ .db "@",0
+ .dw VE_HEAD
+ .set VE_HEAD = VE_FETCH
+XT_FETCH:
+ .dw PFA_FETCH
+PFA_FETCH:
+.if WANT_UNIFIED == 1
+ ldi zh, high(RAMEND)
+ ldi zl, low(RAMEND)
+ cp tosl, zl
+ cpc tosh, zh
+ brlt PFA_FETCHRAM
+ brbs 1, PFA_FETCHRAM
+ rjmp PFA_FETCHOTHER
+.endif
+PFA_FETCHRAM:
+ movw zl, tosl
+ ; low byte is read before the high byte
+ ld tosl, z+
+ ld tosh, z+
+ jmp_ DO_NEXT
+.if WANT_UNIFIED == 1
+PFA_FETCHOTHER:
+ adiw zl, 1
+ sub tosl, zl
+ sbc tosh, zh
+ jmp_ PFA_FETCHE
+.endif