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Refactoring and cleanup.

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This commit is contained in:
Simon Forman
2019-11-09 18:15:56 -08:00
parent 04b021846a
commit 67583716f2
3 changed files with 54 additions and 70 deletions
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thun/compiler.markII.pl
+15 -31
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@@ -44,31 +44,17 @@ Mark II
mov_imm(TERM, 0),
store_word(TOS, SP, 0), % RAM[SP] := 0
label(Main)],
⟐([
label(Main)
],⟐([
if_zero(EXPR_addr, HALT),
load(EXPR, EXPR_addr)
]),[
load(EXPR, EXPR_addr),
% At this point EXPR holds the record word of the expression.
lsl_imm(TermAddr, EXPR, 2), % Trim off the type tag 00 bits.
asr_imm(TermAddr, TermAddr, 17), % preserve sign of offset.
eq_offset(Foo), % if the offset is zero don't add the address. it's empty list.
add(TermAddr, TermAddr, EXPR_addr),
label(Foo),
unpack_pair(EXPR, TermAddr, TEMP0, EXPR_addr),
load(TERM, TermAddr)
]),[
% TermAddr has the address of the term record.
load_word(TERM, TermAddr, 0), % Bring the record in from RAM.
% Now Term has the term's record data and TermAddr has the address of the term.
lsl_imm(TEMP0, EXPR, 17), % Get the offset of the tail of the expr
asr_imm(TEMP0, TEMP0, 17), % while preserving the sign.
eq_offset(Foo0), % if the offset is zero don't add the address. it's empty list.
add(TEMP0, TEMP0, EXPR_addr), % Add the address to the offset.
label(Foo0),
% Now TERM has the term's record data and TermAddr has the address of the term.
mov(EXPR_addr, TEMP0),
% EXPR_addr now holds the address of the next cell of the expression list.
% if_literal(TERM, PUSH),
@@ -110,33 +96,31 @@ Mark II
% ======================================
label(Cons) % Let's cons.
],⟐([
],⟐([
unpack_pair(TOS, TEMP0, TOS, SP),
% TEMP0 = Address of the list to which to append.
% TOS = Address of the second stack cell.
load(TEMP1, TOS),
% TEMP1 contains the record of the second stack cell.
unpack_pair(TEMP1, TEMP2, TEMP3, TOS)
]),[
]),[
% TEMP2 contains the address of the second item on the stack
% TEMP3 = TOS + TEMP1[15:0] the address of the third stack cell
% Build and write the new list cell.
sub_imm(SP, SP, 4)
],⟐([
],⟐([
sub_base_from_offset(TEMP2, SP),
sub_base_from_offset(TEMP0, SP)
]),[
]),[
lsl_imm(TEMP2, TEMP2, 15), % TEMP2 := TEMP2 << 15
ior(TEMP2, TEMP2, TEMP0),
store_word(TEMP2, SP, 0),
sub_imm(SP, SP, 4) ],⟐(
sub_base_from_offset(TEMP3, SP) ),[
sub_imm(SP, SP, 4)
],⟐(
sub_base_from_offset(TEMP3, SP)
),[
mov_imm_with_shift(TOS, 2), % TOS := 4 << 15
ior(TOS, TOS, TEMP3),
do_offset(Done), % Rely on mainloop::Done to write TOS to RAM.