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[Maintenance] Add a VRAM offset roll macro 

Part of P0235, funded by Ember2528.
This commit is contained in:
nmlgc 2023-03-24 02:26:45 +01:00
parent 6a92122432
commit 0e103c6f88
2 changed files with 11 additions and 5 deletions
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9
planar.h
View File

@ -84,6 +84,15 @@ typedef uint16_t uvram_offset_t;
#define VRAM_OFFSET_SHIFT(x, y) \
(x >> BYTE_BITS) + (y << 6) + (y << 4)
// Adds [imm] to [vo] and rolls [vo] back to the top of VRAM if it crossed the
// bottom. Necessary with hardware scrolling.
#define vram_offset_add_and_roll(vo, imm) { \
vo += imm; \
if(static_cast<vram_offset_t>(vo) >= PLANE_SIZE) { \
vo -= PLANE_SIZE; \
} \
}
#ifdef __cplusplus
// MODDERS: Replace with a single function
static inline vram_offset_t vram_offset_shift(screen_x_t x, vram_y_t y) {

7
th02/main/bullet/pellet_r.cpp
View File

@ -18,10 +18,7 @@ void pascal near pellet_render(screen_x_t left, vram_y_t top)
_CX = 8;
put_loop: {
asm { movsw; }
_DI += (ROW_SIZE - sizeof(dots16_t));
if(static_cast<int16_t>(_DI) >= PLANE_SIZE) {
_DI -= PLANE_SIZE;
}
vram_offset_add_and_roll(_DI, (ROW_SIZE - sizeof(dots16_t)));
asm { loop put_loop; }
}
asm { loop put_loop; }
}