From e691dab070209874a44aa7ae6037e68dfa238d05 Mon Sep 17 00:00:00 2001
From: Virgil Dupras <hsoft@hardcoded.net>
Date: Fri, 13 Dec 2019 10:23:11 -0500
Subject: [PATCH] zasm: little drive-by optimization

Use IX directly for argspec rows instead of going through DE. It saves a bit
of processing. The code was this way because I initially didn't use IX at all,
so as code evolved, that DE translation stayed as an artifact.
---
 apps/zasm/instr.asm               | 59 +++++++++++++------------------
 tools/tests/unit/runtests.sh      |  4 ++-
 tools/tests/unit/test_z_instr.asm | 36 +++++++++----------
 3 files changed, 45 insertions(+), 54 deletions(-)

diff --git a/apps/zasm/instr.asm b/apps/zasm/instr.asm
index 85e0464..7e98f10 100644
--- a/apps/zasm/instr.asm
+++ b/apps/zasm/instr.asm
@@ -417,26 +417,6 @@ matchArg:
 	dec	hl
 	ret
 
-; Compare primary row at (DE) with ID in A. Sets Z flag if there's a match.
-matchPrimaryRow:
-	push	hl
-	push	ix
-	push	de \ pop ix
-	cp	(ix)
-	jr	nz, .end
-	; name matches, let's see the rest
-	ld	hl, INS_CURARG1
-	ld	a, (ix+1)
-	call	matchArg
-	jr	nz, .end
-	ld	hl, INS_CURARG2
-	ld	a, (ix+2)
-	call	matchArg
-.end:
-	pop	ix
-	pop	hl
-	ret
-
 ; *** Special opcodes ***
 ; The special upcode handling routines below all have the same signature.
 ; Instruction row is at IX and we're expected to perform the same task as
@@ -574,16 +554,13 @@ handleRST:
 	ld	c, 0
 	ret
 
-; Compute the upcode for argspec row at (DE) and arguments in curArg{1,2} and
+; Compute the upcode for argspec row at (IX) and arguments in curArg{1,2} and
 ; writes the resulting upcode to IO.
 ; A is zero, with Z set, on success. A is non-zero, with Z unset, on error.
 spitUpcode:
-	push	ix
 	push	de
 	push	hl
 	push	bc
-	; First, let's go in IX mode. It's easier to deal with offsets here.
-	push	de \ pop ix
 
 	; before we begin, are we in a 'l' argspec? Is it flagged for IX/IY
 	; acceptance? If yes, a 'x' or 'y' instruction? Check this on both
@@ -823,7 +800,6 @@ spitUpcode:
 	pop	bc
 	pop	hl
 	pop	de
-	pop	ix
 	ret
 .checkCB:
 	ld	a, (INS_UPCODE)
@@ -876,7 +852,7 @@ parseInstruction:
 	push	bc
 	push	hl
 	push	de
-	; A is reused in matchPrimaryRow but that register is way too changing.
+	; A is reused in .matchPrimaryRow but that register is way too changing.
 	; Let's keep a copy in a more cosy register.
 	ld	c, a
 	xor	a
@@ -899,24 +875,24 @@ parseInstruction:
 	; To speed up things a little, we use a poor man's indexing. Full
 	; bisecting would involve too much complexity.
 	ld	a, c			; recall A param
-	ld	de, instrTBl
+	ld	ix, instrTBl
 	cp	I_EX
 	jr	c, .loop
-	ld	de, instrTBlEX
+	ld	ix, instrTBlEX
 	cp	I_LD
 	jr	c, .loop
-	ld	de, instrTBlLD
+	ld	ix, instrTBlLD
 	cp	I_RET
 	jr	c, .loop
-	ld	de, instrTBlRET
+	ld	ix, instrTBlRET
 .loop:
 	ld	a, c			; recall A param
-	call	matchPrimaryRow
+	call	.matchPrimaryRow
 	jr	z, .match
-	ld	a, INSTR_TBL_ROWSIZE
-	call	addDE
-	ld	a, (de)
-	cp	0xff
+	ld	de, INSTR_TBL_ROWSIZE
+	add	ix, de
+	ld	a, 0xff
+	cp	(ix)
 	jr	nz, .loop
 	; No signature match
 	ld	a, ERR_BAD_ARG
@@ -936,6 +912,19 @@ parseInstruction:
 	pop	bc
 	ret
 
+; Compare primary row at (IX) with ID in A. Sets Z flag if there's a match.
+.matchPrimaryRow:
+	cp	(ix)
+	ret	nz
+	; name matches, let's see the rest
+	ld	hl, INS_CURARG1
+	ld	a, (ix+1)
+	call	matchArg
+	ret	nz
+	ld	hl, INS_CURARG2
+	ld	a, (ix+2)
+	jp	matchArg
+
 
 ; In instruction metadata below, argument types arge indicated with a single
 ; char mnemonic that is called "argspec". This is the table of correspondence.
diff --git a/tools/tests/unit/runtests.sh b/tools/tests/unit/runtests.sh
index 0d3cbd8..78566c8 100755
--- a/tools/tests/unit/runtests.sh
+++ b/tools/tests/unit/runtests.sh
@@ -1,4 +1,6 @@
-#!/bin/sh -e
+#!/usr/bin/env bash
+set -e
+# TODO: find POSIX substitute to that PIPESTATUS thing
 
 BASE=../../..
 TOOLS=../..
diff --git a/tools/tests/unit/test_z_instr.asm b/tools/tests/unit/test_z_instr.asm
index 96bf755..8b74036 100644
--- a/tools/tests/unit/test_z_instr.asm
+++ b/tools/tests/unit/test_z_instr.asm
@@ -46,15 +46,15 @@ runTests:
 	halt
 
 testSpitUpcode:
-	ld	ix, .t1
+	ld	iy, .t1
 	call	.test
-	ld	ix, .t2
+	ld	iy, .t2
 	call	.test
-	ld	ix, .t3
+	ld	iy, .t3
 	call	.test
-	ld	ix, .t4
+	ld	iy, .t4
 	call	.test
-	ld	ix, .t5
+	ld	iy, .t5
 	call	.test
 	ret
 
@@ -66,36 +66,36 @@ testSpitUpcode:
 	ld	(SPITBOWL+1), a
 	ld	(SPITBOWL+2), a
 	ld	(SPITBOWL+3), a
-	push	ix \ pop de
-	call	intoDE
-	ld	a, (ix+2)
+	push	iy \ pop ix
+	call	intoIX
+	ld	a, (iy+2)
 	ld	(INS_CURARG1), a
-	ld	a, (ix+3)
+	ld	a, (iy+3)
 	ld	(INS_CURARG1+1), a
-	ld	a, (ix+4)
+	ld	a, (iy+4)
 	ld	(INS_CURARG1+2), a
-	ld	a, (ix+5)
+	ld	a, (iy+5)
 	ld	(INS_CURARG2), a
-	ld	a, (ix+6)
+	ld	a, (iy+6)
 	ld	(INS_CURARG2+1), a
-	ld	a, (ix+7)
+	ld	a, (iy+7)
 	ld	(INS_CURARG2+2), a
 	call	spitUpcode
 	jp	nz, fail
 	ld	a, (SPITCNT)
-	cp	(ix+8)
+	cp	(iy+8)
 	jp	nz, fail
 	ld	a, (SPITBOWL)
-	cp	(ix+9)
+	cp	(iy+9)
 	jp	nz, fail
 	ld	a, (SPITBOWL+1)
-	cp	(ix+10)
+	cp	(iy+10)
 	jp	nz, fail
 	ld	a, (SPITBOWL+2)
-	cp	(ix+11)
+	cp	(iy+11)
 	jp	nz, fail
 	ld	a, (SPITBOWL+3)
-	cp	(ix+12)
+	cp	(iy+12)
 	jp	nz, fail
 	jp	nexttest