78 lines
1.6 KiB
NASM
78 lines
1.6 KiB
NASM
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xxd:
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// a0: source address
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// a1: source length
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// a2: destination (string) address
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// a3: destination (string) maximum length
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// v0: error code (0 is OK)
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beqz a1, xxdExit
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lli v0, 0 // delay slot
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lli v1, 0x20 // ascii space
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xxdLoop:
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lbu t0, 0(a0)
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subiu a1, a1, 1
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addiu a0, a0, 1
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// split byte into nybbles
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srl t1, t0, 4
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andi t0, t0, 0xF
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// convert nybbles to ascii bytes
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sltiu at, t0, 0xA
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bnez at,+
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addiu t2, t0, 0x30 // (delay slot)
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addiu t2, t0, 0x41 - 0xA
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+
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sltiu at, t1, 0xA
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bnez at,+
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addiu t3, t1, 0x30 // (delay slot)
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addiu t3, t1, 0x41 - 0xA
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+
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subiu a3, a3, 3
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blezl a3, xxdExit
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lli v0, 1
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sb v1, 0(a2) // write space
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sb t3, 1(a2) // write high nybble
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sb t2, 2(a2) // write low nybble
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addiu a2, a2, 3
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// pretty-printing:
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andi at, a0, 0xF
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bnez at,+
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lli t9, 0x0A // (delay slot) ascii newline
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subiu a3, a3, 1
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blezl a3, xxdExit
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lli v0, 1
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sb t9, 0(a2) // write newline
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b ++
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addiu a2, a2, 1 // delay slot
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+
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andi at, a0, 0x3
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bnez at,+
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nop // delay slot
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subiu a3, a3, 1
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blezl a3, xxdExit
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lli v0, 1
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sb v1, 0(a2) // write extra space
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addiu a2, a2, 1
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+
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bnez a1, xxdLoop
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nop // delay slot
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beqz a3, xxdExit
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nop // delay slot
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xxdZero:
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// fill the remaining bytes with nulls
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sb r0, 0(a2)
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subiu a3, a3, 1
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bnez a3, xxdZero
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addiu a2, a2, 1 // delay slot
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xxdExit:
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jr ra
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nop // delay slot
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