140 lines
4.6 KiB
NASM
140 lines
4.6 KiB
NASM
.text
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#initialize $sp
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lui $sp, 0x4000
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addi $sp, $sp, 0x7ff
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# load digit to mem
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lui $s0, 0x4000
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addi $s0, $s0, 0x20
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#0
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addi $s1, $zero, 0x3f
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sw $s1, 0($s0)
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#1
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addi $s1, $zero, 0x6
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sw $s1, 4($s0)
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#2
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addi $s1, $zero, 0x5b
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sw $s1, 8($s0)
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#3
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addi $s1, $zero, 0x4f
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sw $s1, 12($s0)
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#4
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addi $s1, $zero, 0x66
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sw $s1, 16($s0)
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#5
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addi $s1, $zero, 0x6d
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sw $s1, 20($s0)
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#6
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addi $s1, $zero, 0x7d
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sw $s1, 24($s0)
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#7
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addi $s1, $zero, 0x7
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sw $s1, 28($s0)
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#8
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addi $s1, $zero, 0x7f
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sw $s1, 32($s0)
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#9
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addi $s1, $zero, 0x6f
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sw $s1, 36($s0)
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#A
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addi $s1, $zero, 0x77
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sw $s1, 40($s0)
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#B
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addi $s1, $zero, 0x7c
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sw $s1, 44($s0)
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#C
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addi $s1, $zero, 0x58
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sw $s1, 48($s0)
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#D
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addi $s1, $zero, 0x5e
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sw $s1, 52($s0)
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#E
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addi $s1, $zero, 0x79
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sw $s1, 56($s0)
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#F
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addi $s1, $zero, 0x71
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sw $s1, 60($s0)
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lui $s1, 0x4000
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addi $s1, $s1, 0x10
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addi $s0, $zero, 0xa80
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main_loop:
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addi $s0, $s0, 1
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addi $a0, $s0, 0
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addi $a1, $s1, 0
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jal display_number
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j main_loop
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# a0 is the number to be displayed, a1 is the bcd control addr
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display_number:
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addi $sp, $sp, -32
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sw $ra, 4($sp)
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sw $s0, 8($sp)
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sw $s1, 12($sp)
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sw $s2, 16($sp)
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sw $s3, 20($sp)
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sw $s4, 24($sp)
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sw $s5, 28($sp)
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sw $s6, 32($sp)
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# s0 is the number to be displayed
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addi $s0, $a0, 0
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# s1 is the bcd_control addr
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addi $s1, $a1, 0
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# s2 is the base addr for display digit
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lui $s2, 0x4000
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addi $s2, $s2, 0x20
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# s3 is the counter for a complete scan of 4 digit
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addi $s3, $zero, 0xbe2
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all_digit_scan_loop:
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# s4 is the num being shifted gradually
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addi $s4, $s0, 0
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# s6 is the enable digit
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addi $s6, $zero, 0x100
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addi $s5, $zero, 4
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single_digit_loop:
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# get a digit
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andi $t0, $s4, 0xf
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# digit * 4 is the memory shift
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sll $t0, $t0, 2
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add $t0, $s2, $t0
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lw $t0, 0($t0)
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or $t0, $t0, $s6
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sw $t0, 0($s1)
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srl $s4, $s4, 4
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sll $s6, $s6, 1
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# jal wait_for_digit_time
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addi $t0, $zero, 0x400
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wait_time_loop:
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addi $t0, $t0, -1
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bgtz $t0, wait_time_loop
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addi $s5, $s5, -1
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bgtz $s5, single_digit_loop
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# end of single digit loop
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# ** depends on the clock **
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# four digit, 328.68us.
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# 1s / 328.68us = 3042 = (be2)hex
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addi $s3, $s3, -1
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bgtz $s3, all_digit_scan_loop
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lw $ra, 4($sp)
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lw $s0, 8($sp)
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lw $s1, 12($sp)
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lw $s2, 16($sp)
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lw $s3, 20($sp)
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lw $s4, 24($sp)
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lw $s5, 28($sp)
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lw $s6, 32($sp)
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addi $sp, $sp, 32
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jr $ra
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