A dungeon delver roguelike using Pathfinder 2nd edition rules
Adding random number generator
+54
-1
+7
gb/src/dungeon.asm
+7
gb/src/dungeon.asm
+12
-1
gb/src/main.asm
+12
-1
gb/src/main.asm
···
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INCLUDE "hardware.inc/hardware.inc"
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rev_Check_hardware_inc 4.0
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3
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SECTION "GameVariables", WRAM0
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randstate:: ds 4
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SECTION "Header", ROM0[$100]
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; This is your ROM's entry point
···
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EntryPoint:
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; Here is where the fun begins, happy coding :)
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jr @
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ld b, 0
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ld c, 10
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call srand
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call rand
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jp Done
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Done:
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jp Done
+35
gb/src/utils.asm
+35
gb/src/utils.asm
···
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SECTION "Math", ROM0
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;; From: https://github.com/pinobatch/libbet/blob/master/src/rand.z80#L34-L54
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; Generates a pseudorandom 16-bit integer in BC
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; using the LCG formula from cc65 rand():
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; x[i + 1] = x[i] * 0x01010101 + 0xB3B3B3B3
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; @return A=B=state bits 31-24 (which have the best entropy),
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; C=state bits 23-16, HL trashed
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rand::
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; Add 0xB3 then multiply by 0x01010101
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ld hl, randstate+0
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ld a, [hl]
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add a, $B3
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ld [hl+], a
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adc a, [hl]
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ld [hl+], a
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adc a, [hl]
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ld [hl+], a
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ld c, a
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adc a, [hl]
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ld [hl], a
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ld b, a
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ret
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; Sets the random seed to BC.
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; C expects startup code to behave as if srand(1) was called.
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; AHL trashed
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srand::
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ld hl,randstate+3
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xor a
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ld [hl-],a
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ld [hl-],a
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ld a,b
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ld [hl-],a
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ld [hl],c
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ret