small cleanup in BASIC
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@@ -2,14 +2,12 @@
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// #LAYOUT# * BASIC_0 #TAKE
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// #LAYOUT# * * #IGNORE
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// Delete the current BASIC line, which is assumed to have already
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// been found with find_line.
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// Really only consists of copying memory down.
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// The only complication is that we have to do the copy with ROMs
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// banked out. Oh, yes, and we have to update all the links in
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// the following basic lines.
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//
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// Delete the current BASIC line, which is assumed to have already been found with find_line.
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// Consists of copying memory down and lline linkage update.
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//
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basic_delete_line:
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delete_line:
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// jsr printf
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// .text "DELETING LINE AT $"
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@@ -61,6 +59,7 @@ basic_delete_line:
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sbc #0
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cmp #$00
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beq !+
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// Line length is <0 or >255 bytes.
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// Either way, things are bad, so abort.
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jmp do_MEMORY_CORRUPT_error
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@@ -2,17 +2,18 @@
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// #LAYOUT# * BASIC_0 #TAKE
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// #LAYOUT# * * #IGNORE
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//
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// Insert the tokenised line stored at $0200.
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// First work out where in the list to put it
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// (basic_find_line with the line number can be used to work
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// out the insertion point, as it should abort once it finds a
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// line number too high).
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//
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// First work out where in the list to put it (find_line with the line number can be used to work
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// out the insertion point, as it should abort once it finds a line number too high).
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// Then all we have to do is push the rest of the BASIC text up,
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// and update the pointers in all following basic lines.
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//
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basic_insert_line:
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insert_line:
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// ASSUMES basic_find_line has been called to set the insert point.
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// ASSUMES find_line has been called to set the insert point.
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// We need to insert space for the link link token, the line number,
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// and the zero-terminated line itself. This means 2+2+1 plus length
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// of tokenised string after the line number
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@@ -36,6 +37,7 @@ basic_insert_line:
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lda __tokenise_work2
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sec
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sbc __tokenise_work1
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// Add on the four bytes space we need
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clc
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adc #5
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@@ -82,7 +84,7 @@ basic_insert_line:
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// Now store the line body itself
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inc __tokenise_work2
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line_store_loop:
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!:
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ldx __tokenise_work1
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lda $0200,x
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inc __tokenise_work1
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@@ -97,7 +99,7 @@ line_store_loop:
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lda __tokenise_work1
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cmp __tokenise_work2
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bne line_store_loop
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bne !-
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dec __tokenise_work2
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clc
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@@ -148,24 +148,22 @@ shell_add_delete_line:
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// First, clear all variables, so that we only have to shove BASIC text around
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jsr basic_do_clr
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.break
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// Delete line if present
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// Check if line already present
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jsr find_line
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// XXX
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bcs !+
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// Delete the line, whether we are deleting or
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// replacing the line
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jsr basic_delete_line
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// Line already present - delete it
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.break
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jsr delete_line
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!:
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// Insert new line if non-zero length, i.e., that
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// we are not just deleting the line.
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lda __tokenise_work1
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cmp __tokenise_work2
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beq !+
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jsr basic_insert_line
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jsr insert_line
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!:
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// No READY message after entering or deleting a line of BASIC
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jmp shell_read_next_line
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