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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/umslashmod.asm
parente0d6784e89dba33226c0edb815bb974486fa7c48 (diff)
Add AmForth
Diffstat (limited to 'amforth-6.5/avr8/words/umslashmod.asm')
-rw-r--r--amforth-6.5/avr8/words/umslashmod.asm62
1 files changed, 62 insertions, 0 deletions
diff --git a/amforth-6.5/avr8/words/umslashmod.asm b/amforth-6.5/avr8/words/umslashmod.asm
new file mode 100644
index 0000000..6adfbb1
--- /dev/null
+++ b/amforth-6.5/avr8/words/umslashmod.asm
@@ -0,0 +1,62 @@
+; ( ud u2 -- rem quot)
+; Arithmetics
+; unsigned division ud / u2 with remainder
+VE_UMSLASHMOD:
+ .dw $ff06
+ .db "um/mod"
+ .dw VE_HEAD
+ .set VE_HEAD = VE_UMSLASHMOD
+XT_UMSLASHMOD:
+ .dw PFA_UMSLASHMOD
+PFA_UMSLASHMOD:
+ movw temp4, tosl
+
+ ld temp2, Y+
+ ld temp3, Y+
+
+ ld temp0, Y+
+ ld temp1, Y+
+
+;; unsigned 32/16 -> 16r16 divide
+
+PFA_UMSLASHMODmod:
+
+ ; set loop counter
+ ldi temp6,$10
+
+PFA_UMSLASHMODmod_loop:
+ ; shift left, saving high bit
+ clr temp7
+ lsl temp0
+ rol temp1
+ rol temp2
+ rol temp3
+ rol temp7
+
+ ; try subtracting divisor
+ cp temp2, temp4
+ cpc temp3, temp5
+ cpc temp7,zerol
+
+ brcs PFA_UMSLASHMODmod_loop_control
+
+PFA_UMSLASHMODmod_subtract:
+ ; dividend is large enough
+ ; do the subtraction for real
+ ; and set lowest bit
+ inc temp0
+ sub temp2, temp4
+ sbc temp3, temp5
+
+PFA_UMSLASHMODmod_loop_control:
+ dec temp6
+ brne PFA_UMSLASHMODmod_loop
+
+PFA_UMSLASHMODmod_done:
+ ; put remainder on stack
+ st -Y,temp3
+ st -Y,temp2
+
+ ; put quotient on stack
+ movw tosl, temp0
+ jmp_ DO_NEXT