From 4b9596e8923982a3ae190b60ab1f4be56e7f2c4c Mon Sep 17 00:00:00 2001
From: Leo Tenenbaum <pommicket@gmail.com>
Date: Sat, 20 Nov 2021 12:47:26 -0500
Subject: looking up things

---
 04b/in03  | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 04b/in04b |  10 +++---
 2 files changed, 105 insertions(+), 9 deletions(-)

diff --git a/04b/in03 b/04b/in03
index 62b9bfc..0995296 100644
--- a/04b/in03
+++ b/04b/in03
@@ -153,6 +153,10 @@ D=A
 	J=d0
 	syscall x3c
 
+align
+:local_start
+	reserve d8
+	
 :handle_local
 	R=I
 	
@@ -168,6 +172,18 @@ D=A
 	call :read_type
 	R=A
 	I+=d1
+	
+	; check if already defined
+	C=:local_start
+	8C=I
+	J=:local_variables
+	D=d9
+	call :ident_lookup
+	C=A
+	?C!0:local_redeclaration
+	C=:local_start
+	I=8C
+	
 	J=:local_variables_end
 	J=8J
 	call :ident_copy
@@ -201,8 +217,11 @@ D=A
 	x00
 	x00
 
+align
+:global_start
+	reserve d8
+
 :handle_global
-	; @TODO: check if already exists
 	; skip ' '
 	I+=d1
 	call :read_type
@@ -210,6 +229,19 @@ D=A
 	R=A
 	; skip ' ' after type
 	I+=d1
+	
+	; check if already defined
+	C=:global_start
+	8C=I
+	J=:global_variables
+	D=d9
+	call :ident_lookup
+	C=A
+	?C!0:global_redeclaration
+	C=:global_start
+	I=8C
+	
+	
 	J=:global_variables_end
 	J=8J
 	call :ident_copy
@@ -269,7 +301,13 @@ D=A
 		!:bad_label
 	:label_checking_loop_end
 	
-	; @TODO: check if already exists
+	I=:line
+	I+=d1
+	J=:labels
+	D=d4
+	call :ident_lookup
+	C=A
+	?C!0:label_redefinition
 	
 	J=:labels_end
 	J=8J
@@ -343,8 +381,36 @@ D=A
 		!:ident_loop
 	:ident_loop_end
 	return
-		
 
+align
+:ident_lookup_i
+	reserve d8
+:ident_lookup_sep
+	reserve d8
+
+; look up identifier rsi in list rdi with separation rdx between entries
+; returns address of whatever's right after the identifier in the list, or 0 if not found
+:ident_lookup
+	C=:ident_lookup_sep
+	8C=D
+	C=:ident_lookup_i
+	8C=I
+	
+	:ident_lookup_loop
+		I=:ident_lookup_i
+		I=8I
+		call :ident=
+		C=A
+		; move past terminator
+		J+=d1
+		?C!0:return_J
+		C=:ident_lookup_sep
+		C=8C
+		J+=C
+		C=1J
+		?C=0:return_0
+		!:ident_lookup_loop
+		
 ; can the character in rbx appear in an identifier?
 :isident
 	A='0
@@ -466,6 +532,33 @@ D=A
 	xa
 	x0
 
+:label_redefinition
+	B=:label_redefinition_error_message
+	!:program_error
+
+:label_redefinition_error_message
+	str Label redefinition.
+	xa
+	x0
+
+:global_redeclaration
+	B=:global_redeclaration_error_message
+	!:program_error
+
+:global_redeclaration_error_message
+	str Global variable declared twice.
+	xa
+	x0
+
+:local_redeclaration
+	B=:local_redeclaration_error_message
+	!:program_error
+
+:local_redeclaration_error_message
+	str Local variable declared twice.
+	xa
+	x0
+
 :general_error
 	call :eputs
 	J=d1
@@ -580,7 +673,10 @@ D=A
 :return_8
 	A=d8
 	return
-
+:return_J
+	A=J
+	return
+	
 ; write the character in rbx to the file in rdi.
 :fputc
 	C=B
diff --git a/04b/in04b b/04b/in04b
index 06da723..a6e76b9 100644
--- a/04b/in04b
+++ b/04b/in04b
@@ -11,7 +11,7 @@
 ;     <lvalue> += <rvalue>
 ;     <lvalue> -= <rvalue>
 ;     <function>(<term>, <term>, ...)
-;     syscall(<term>, <term>, ...)
+;     syscall <term>, <term>, ...
 ;     return <rvalue>
 ;     byte <number>
 ; term:
@@ -33,7 +33,7 @@
 ;     <var>[<term>]
 ;     ~<var>
 ;     <function>(<term>, <term>, ...)
-;     syscall(<term>, <term>, ...)
+;     syscall <term>, <term>, ...
 ;     <term> + <term>
 ;     <term> - <term>
 ;    NOTE: *, /, % are signed (imul and idiv)
@@ -71,7 +71,7 @@ function
 	argument char c
 	local *char p
 	p = &c
-	syscall(1, 1, p, 1, 0, 0, 0, 0)
+	syscall 1, 1, p, 1, 0, 0, 0, 0
 	return
 
 :puts
@@ -79,7 +79,7 @@ function
 	argument *char s
 	local long len
 	len = strlen(s)
-	syscall(1, 1, s, len, 0, 0, 0, 0)
+	syscall 1, 1, s, len, 0, 0, 0, 0
 	return
 
 :main
@@ -88,7 +88,7 @@ function
 	hello = `Hello, world!
 `
 	puts(hello)
-	syscall(0x3c, 0, 0, 0, 0, 0, 0, 0)
+	syscall 0x3c, 0, 0, 0, 0, 0, 0, 0
 
 
 :f
-- 
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