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42 lines
809 B
Plaintext
42 lines
809 B
Plaintext
// Routines from C64 BASIC ROM
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import c64_kernal
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// print a 16-bit number on the standard output
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asm void putword(word xa) @$BDCD extern
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asm void readline() @$A560 extern
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const pointer readline_out = $200
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byte readword_err
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word readword() {
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readline()
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readword_err = 0
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word result
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word four
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result = 0
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byte char
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byte i
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i = 0
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while true {
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char = readline_out[i]
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if char == 0 {
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if i == 0 {
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readword_err = 1
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}
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return result
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}
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if 48 <= char <= 48+9 {
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four = result
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four <<= 2
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result += four
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result <<= 1
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result += char - 48
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} else {
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readword_err = 1
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return result
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}
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i += 1
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}
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}
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