233 lines
3.9 KiB
ArmAsm
233 lines
3.9 KiB
ArmAsm
// #LAYOUT# STD * #TAKE
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// #LAYOUT# * BASIC_0 #TAKE
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// #LAYOUT# * * #IGNORE
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// This routine prints messages that have been packed
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// using the make_error_tables program.
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// The general idea is to save space in the ROM.
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// The output of make_error_tables is written to packed_messages.s, and
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// contains the following:
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//
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// packed_message_words - List of nybl packed words.
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// packed_message_tokens - List of tokens that get joined to make messages
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// packed_message_chars - List of characters in messages sorted by frequency.
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print_packed_message:
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// .X = message number
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lda #$ff
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ldy #$ff
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packed_message_search:
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iny
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cpx #$00
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beq found_message_in_token_stream
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lda packed_message_tokens,y
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cmp #$ff
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bne !+
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dex
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!:
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cpy #$ff
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bne packed_message_search
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// Could not find message
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sec
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rts
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found_message_in_token_stream: // XXX size-optimize this
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// Now print each word in the message
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phy_trash_a
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lda packed_message_tokens,y
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cmp #$FF
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beq found_message_in_token_stream_done
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jsr print_packed_word
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ply_trash_a
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iny
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beq found_message_in_token_stream_done
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!:
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phy_trash_a
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lda packed_message_tokens,y
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cmp #$FF
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beq found_message_in_token_stream_done
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pha
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jsr print_space
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pla
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jsr print_packed_word
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ply_trash_a
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iny
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bne !-
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found_message_in_token_stream_done:
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pla
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rts
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print_packed_word:
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// A = the word to print
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tax
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// Setup pointer to packed words
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lda #<packed_message_words
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sta FRESPC+0
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lda #>packed_message_words
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sta FRESPC+1
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// Find the word in the list
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ldy #$ff
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packed_word_search:
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iny
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cpx #$00
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beq found_packed_word
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// $x0 is an end of work marker
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lda (FRESPC),y
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and #$0f
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cmp #$00
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bne !+
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dex
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!:
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// $FE $xx is an end of work marker
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lda (FRESPC),y
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cmp #$fe
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bne !+
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dex
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iny // skip next byte
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!:
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cmp #$ff
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bne !+
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iny // skip next byte
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!:
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// Advance to next page if required
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cpy #$ff
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bne packed_word_search
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inc FRESPC+1
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jmp packed_word_search
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found_packed_word:
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// Get pointer to start of packed word
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// Make sure we do not wrap on a page boundary
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tya
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clc
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adc FRESPC+0
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sta FRESPC+0
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lda FRESPC+1
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adc #$00
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sta FRESPC+1
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print_packed_string:
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ldy #$ff
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next_packed_word_char:
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// .Y = offset into packed word data - 1
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iny
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// Check for end of word
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lda (FRESPC),y
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cmp #$00
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beq end_of_packed_word
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cmp #$fe
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beq last_literal
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cmp #$ff
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beq next_is_literal_char
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and #$f0
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beq end_of_packed_word
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// Check if it is an uncommon char
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lda (FRESPC),y
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and #$f0
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cmp #$f0
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beq is_uncommon_char
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// Is not an uncommon char, so get char of upper nybl
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lda (FRESPC),y
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// Put high nybl into low bits of X
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lsr
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lsr
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lsr
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lsr
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tax
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// X=1-14 = first 14 chars, so subtract one
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lda packed_message_chars-1,x
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jsr JCHROUT // preserves .Y
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// See if there is a char in the low nybl to print
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lda (FRESPC),y
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and #$0f
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beq end_of_packed_word
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cmp #$0f
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beq no_lo_nybl_char
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has_lo_nybl_char:
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// We need to print the low nybl char as well
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tax
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phy_trash_a
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// Skip lower nybls of $F or $0 in nybl packed
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// bytes, as these do not encode characters
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cpx #$f
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beq !+
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has_nybl:
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cpx #0
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beq !+
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// X=1-14 = first 14 chars, so subtract one
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lda packed_message_chars-1,x
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jsr JCHROUT
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!:
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ply_trash_a
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// FALLTHROUGH
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no_lo_nybl_char:
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// If current byte has $0F in low nybl, then the next
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// byte is a whole byte.
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lda (FRESPC),y
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and #$0f
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cmp #$0f
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beq next_is_literal_char
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ready_for_next_char:
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cpy #$ff
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bne next_packed_word_char
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end_of_packed_word:
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// Hit end of packed data
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rts
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last_literal:
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jsr unpack_literal_char
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rts
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next_is_literal_char:
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jsr unpack_literal_char
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jmp ready_for_next_char
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unpack_literal_char:
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// Output the literal char, and ready for next char
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iny
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phy_trash_a
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lda (FRESPC),y
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jsr JCHROUT
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pla
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tay
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rts
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is_uncommon_char:
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// Lower nybl has offset into low-frequency part of the table
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lda (FRESPC),y
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and #$0f
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clc
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adc #14
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// We need to print the low nybl char as well
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tax
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phy_trash_a
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jmp has_nybl
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