Dream 44

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Text File | 1995-02-19 | 26KB | 895 lines

; Use the GET directive to include register definitions as if typed here KEEP GET h.WolfReg ; Use the GET directive to include a list of SWI names as if typed here GET h.SWInames ; Area name C$$code advisable as wanted to link with C output AREA |C$$code|, CODE, READONLY ; Export global symbols IMPORT |x$stack_overflow| EXPORT |DrawScaledLineVGA| EXPORT |BigRedrawScreenVGA| DSLineX1 DCB "DrawScaledLine", 0 ALIGN DSLineY1 DCD &ff000000 + DSLineY1 - DSLineX1 ;scale line of graphics block to height value. ;on entry - ; r0 = pointer to Plot_Block where :- ; 0 - 3 = clipped heights of lines to draw ; 4 - 7 = gradients of lines to draw ; 8 - 11 = gradient counters (13 bit resolution) ; 12- 15 = data addresses of graphics data ; 16 = screen address ; 17 = base address of graphics data ; 18 = smallest_height ; 19 = screen height ; 20 = pointer to gradient table ; 21 = scaling factor ; 22 = AND value ALIGN SmallestHeight1 DCD 0 ALIGN |DrawScaledLineVGA| STMFD r13!,{r0-r12,link} ;outer loop ;r0 = pointer to plot block. LDMIA r0,{r1-r3} SUB r1,r1,#16 SUB r2,r2,#16 ADD r3,r3,#4 LDR r4,[r0,#64] ADD r4,r4,#4 STR r4,[r0,#64] STMFD r13!,{r1-r4} OuterLoop LDMFD r13!,{r1-r4} ADD r1,r1,#16 ADD r2,r2,#16 SUBS r3,r3,#4 BEQ EndOuterLoop ADD r4,r4,#4 STR r4,[r0,#64] STMFD r13!,{r1-r4} STMFD r13!,{r2} LDMIA r1,{r5-r8} ;shift distances down 17 places MOV r5,r5,LSR #18 MOV r6,r6,LSR #18 MOV r7,r7,LSR #18 MOV r8,r8,LSR #18 ;clear result registers MOV r1,#0 MOV r2,#0 MOV r3,#0 MOV r4,#0 ;compute heights from distances ;wrk = temp register ;div = divisor (distance) ;num = number (64<<10) ;res = result ;RSBS wrk,div,num,LSR #bit ;ADC res,res,res ;SUBCS num,num,div,LSR #bit ;set up working registers MOV r9,#64 ;num MOV r9,r9,LSL #10 RSBS r14,r5,r9,LSR #16 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #16 RSBS r14,r5,r9,LSR #15 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #15 RSBS r14,r5,r9,LSR #14 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #14 RSBS r14,r5,r9,LSR #13 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #13 RSBS r14,r5,r9,LSR #12 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #12 RSBS r14,r5,r9,LSR #11 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #11 RSBS r14,r5,r9,LSR #10 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #10 RSBS r14,r5,r9,LSR #9 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #9 RSBS r14,r5,r9,LSR #8 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #8 RSBS r14,r5,r9,LSR #7 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #7 RSBS r14,r5,r9,LSR #6 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #6 RSBS r14,r5,r9,LSR #5 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #5 RSBS r14,r5,r9,LSR #4 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #4 RSBS r14,r5,r9,LSR #3 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #3 RSBS r14,r5,r9,LSR #2 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #2 RSBS r14,r5,r9,LSR #1 ADC r1,r1,r1 SUBCS r9,r9,r5,LSL #1 ;set up working registers MOV r9,#64 ;num MOV r9,r9,LSL #10 RSBS r14,r6,r9,LSR #16 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #16 RSBS r14,r6,r9,LSR #15 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #15 RSBS r14,r6,r9,LSR #14 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #14 RSBS r14,r6,r9,LSR #13 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #13 RSBS r14,r6,r9,LSR #12 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #12 RSBS r14,r6,r9,LSR #11 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #11 RSBS r14,r6,r9,LSR #10 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #10 RSBS r14,r6,r9,LSR #9 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #9 RSBS r14,r6,r9,LSR #8 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #8 RSBS r14,r6,r9,LSR #7 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #7 RSBS r14,r6,r9,LSR #6 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #6 RSBS r14,r6,r9,LSR #5 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #5 RSBS r14,r6,r9,LSR #4 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #4 RSBS r14,r6,r9,LSR #3 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #3 RSBS r14,r6,r9,LSR #2 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #2 RSBS r14,r6,r9,LSR #1 ADC r2,r2,r2 SUBCS r9,r9,r6,LSL #1 ;set up working registers MOV r9,#64 ;num MOV r9,r9,LSL #10 RSBS r14,r7,r9,LSR #16 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #16 RSBS r14,r7,r9,LSR #15 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #15 RSBS r14,r7,r9,LSR #14 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #14 RSBS r14,r7,r9,LSR #13 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #13 RSBS r14,r7,r9,LSR #12 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #12 RSBS r14,r7,r9,LSR #11 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #11 RSBS r14,r7,r9,LSR #10 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #10 RSBS r14,r7,r9,LSR #9 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #9 RSBS r14,r7,r9,LSR #8 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #8 RSBS r14,r7,r9,LSR #7 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #7 RSBS r14,r7,r9,LSR #6 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #6 RSBS r14,r7,r9,LSR #5 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #5 RSBS r14,r7,r9,LSR #4 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #4 RSBS r14,r7,r9,LSR #3 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #3 RSBS r14,r7,r9,LSR #2 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #2 RSBS r14,r7,r9,LSR #1 ADC r3,r3,r3 SUBCS r9,r9,r7,LSL #1 ;set up working registers MOV r9,#64 ;num MOV r9,r9,LSL #10 RSBS r14,r8,r9,LSR #16 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #16 RSBS r14,r8,r9,LSR #15 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #15 RSBS r14,r8,r9,LSR #14 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #14 RSBS r14,r8,r9,LSR #13 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #13 RSBS r14,r8,r9,LSR #12 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #12 RSBS r14,r8,r9,LSR #11 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #11 RSBS r14,r8,r9,LSR #10 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #10 RSBS r14,r8,r9,LSR #9 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #9 RSBS r14,r8,r9,LSR #8 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #8 RSBS r14,r8,r9,LSR #7 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #7 RSBS r14,r8,r9,LSR #6 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #6 RSBS r14,r8,r9,LSR #5 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #5 RSBS r14,r8,r9,LSR #4 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #4 RSBS r14,r8,r9,LSR #3 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #3 RSBS r14,r8,r9,LSR #2 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #2 RSBS r14,r8,r9,LSR #1 ADC r4,r4,r4 SUBCS r9,r9,r8,LSL #1 ;multiply by scaling factor LDR r14,[r0,#84] MUL r1,r14,r1 MUL r2,r14,r2 MUL r3,r14,r3 MUL r4,r14,r4 MOV r1,r1,LSR #16 MOV r2,r2,LSR #16 MOV r3,r3,LSR #16 MOV r4,r4,LSR #16 ;shift and round CMP r1,#2 MOVLT r1,#2 CMP r2,#2 MOVLT r2,#2 CMP r3,#2 MOVLT r3,#2 CMP r4,#2 MOVLT r4,#2 MOV r1,r1,ASL #1 MOV r2,r2,ASL #1 MOV r3,r3,ASL #1 MOV r4,r4,ASL #1 ;load pointer to gradient table LDR r5,[r0,#80] ;limit heights MOV r6,#1024 SUB r6,r6,#1 CMP r1,r6 MOVGT r1,r6 CMP r2,r6 MOVGT r2,r6 CMP r3,r6 MOVGT r3,r6 CMP r4,r6 MOVGT r4,r6 MOV r6,#4 CMP r1,r6 MOVLT r1,r6 CMP r2,r6 MOVLT r2,r6 CMP r3,r6 MOVLT r3,r6 CMP r4,r6 MOVLT r4,r6 ;load gradients from table LDR r6,[r5,r1,LSL #2] LDR r7,[r5,r2,LSL #2] LDR r8,[r5,r3,LSL #2] LDR r9,[r5,r4,LSL #2] ADD r0,r0,#16 STMIA r0,{r6-r9} SUB r0,r0,#16 ;load smallest height LDR r5,[r0,#76] ;modify height values SUBS r14,r4,r5 MOVPL r14,r14,LSR #1 MULPL r12,r9,r14 MOVPL r4,r5 MOVMI r12,#0 SUBS r14,r1,r5 MOVPL r14,r14,LSR #1 MULPL r9,r6,r14 MOVPL r1,r5 MOVMI r9,#0 SUBS r14,r2,r5 MOVPL r14,r14,LSR #1 MULPL r10,r7,r14 MOVPL r2,r5 MOVMI r10,#0 SUBS r14,r3,r5 MOVPL r14,r14,LSR #1 MULPL r11,r8,r14 MOVPL r3,r5 MOVMI r11,#0 STMIA r0,{r1-r4} ADD r0,r0,#32 STMIA r0,{r9-r12} SUB r0,r0,#32 ;find smallest height, store in r7 MOV r7,r1 CMP r2,r7 MOVLT r7,r2 CMP r3,r7 MOVLT r7,r3 CMP r4,r7 MOVLT r7,r4 STR r7,[r0,#72] LDMFD r13!,{r9} ;load r11 with graphics data pointer LDR r11,[r0,#68] ;draw upper section of line 1 LDR r2,[r0,#16] ; load gradient of line 1 LDR r3,[r0,#32] ; load gradient counter for line 1 LDR r4,[r9] ; load data address of data for line 1 ADD r3,r3,r4,LSL #14 ; combine gradient counter & data addr SUB r14,r1,r7 ; get height offset against smallest height MOVS r14,r14,LSR #1 STREQ r3,[r0,#32] ; save gradient counter for line 1 BEQ DrawLine2 LDR r5,[r0,#64] ; load screen address RSB r6,r1,#480 ; find distance from top of screen MOV r6,r6,LSR #1 MOV r8,r6,LSL #6 ; multiply height offset by 128 ADD r6,r8,r6,LSL #8 ; add to height offset * *256 ADD r5,r5,r6,LSL #1 ; add to screen base MOV r1,r14 BL DrawByteLine STR r3,[r0,#32] ; save gradient counter for line 1 DrawLine2 ;draw upper section of line 2 LDR r2,[r0,#20] ; load gradient of line 2 LDR r3,[r0,#36] ; load gradient counter for line 2 LDR r4,[r9,#4] ; load data address of data for line 2 ADD r3,r3,r4,LSL #14 ; combine gradient counter & data addr LDR r1,[r0,#4] SUB r14,r1,r7 ; get height offset against smallest height MOVS r14,r14,LSR #1 STREQ r3,[r0,#36] ; save gradient counter for line 2 BEQ DrawLine3 LDR r5,[r0,#64] ; load screen address RSB r6,r1,#480 ; find distance from top of screen MOV r6,r6,LSR #1 MOV r8,r6,LSL #6 ; multiply height offset by 128 ADD r6,r8,r6,LSL #8 ; add to height offset * 256 ADD r5,r5,r6,LSL #1 ; add to screen base ADD r5,r5,#1 MOV r1,r14 BL DrawByteLine STR r3,[r0,#36] ; save gradient counter for line 2 DrawLine3 ;draw upper section of line 3 LDR r2,[r0,#24] ; load gradient of line 3 LDR r3,[r0,#40] ; load gradient counter for line 3 LDR r4,[r9,#8] ; load data address of data for line 3 ADD r3,r3,r4,LSL #14 ; combine gradient counter & data addr LDR r1,[r0,#8] SUB r14,r1,r7 ; get height offset against smallest height MOVS r14,r14,LSR #1 STREQ r3,[r0,#40] ; save gradient counter for line 3 BEQ DrawLine4 LDR r5,[r0,#64] ; load screen address RSB r6,r1,#480 ; find distance from top of screen MOV r6,r6,LSR #1 MOV r8,r6,LSL #6 ; multiply height offset by 64 ADD r6,r8,r6,LSL #8 ; add to height offset * 256 ADD r5,r5,r6,LSL #1 ; add to screen base ADD r5,r5,#2 MOV r1,r14 BL DrawByteLine STR r3,[r0,#40] ; save gradient counter for line 3 DrawLine4 ;draw upper section of line 4 LDR r1,[r0,#12] LDR r2,[r0,#28] ; load gradient of line 4 LDR r3,[r0,#44] ; load gradient counter for line 4 LDR r4,[r9,#12] ; load data address of data for line 4 ADD r3,r3,r4,LSL #14 ; combine gradient counter & data addr SUB r14,r1,r7 ; get height offset against smallest height MOVS r14,r14,LSR #1 STREQ r3,[r0,#44] ; save gradient counter for line 4 BEQ DrawMainBlock LDR r5,[r0,#64] ; load screen address RSB r6,r1,#480 ; find distance from top of screen MOV r6,r6,LSR #1 MOV r8,r6,LSL #6 ; multiply height offset by 64 ADD r6,r8,r6,LSL #8 ; add to height offset * 256 ADD r5,r5,r6,LSL #1 ; add to screen base ADD r5,r5,#3 MOV r1,r14 BL DrawByteLine STR r3,[r0,#44] ; save gradient counter for line 4 DrawMainBlock ;preserve smallest height LDR r14,[r0,#72] LDR r12,[r0,#64] ; load screen address ;compute screen address LDR r5,[r0,#64] ; load screen address RSB r6,r14,#480 ; find distance from top of screen MOV r6,r6,LSR #1 MOV r8,r6,LSL #6 ; multiply height offset by 64 ADD r6,r8,r6,LSL #8 ; add to height offset * 256 ADD r12,r5,r6,LSL #1 ; add to screen base ;load and combine AND value with counter LDR r9,[r0,#88] ORR r14,r14,r9 ADD r0,r0,#16 LDMIA r0!,{r1-r4} ; load up gradients LDMIA r0,{r5-r8} ; load up gradient counters + data addrs StartPlotBlock LDRB r10,[r11,r5,LSR #14] AND r10,r10,r14,LSR #16 LDRB r9,[r11,r6,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #8 LDRB r9,[r11,r7,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #16 LDRB r9,[r11,r8,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #24 STR r10,[r12],#320 STR r10,[r12],#320 ADD r5,r5,r1 ADD r6,r6,r2 ADD r7,r7,r3 ADD r8,r8,r4 SUB r14,r14,#1 MOVS r10,r14,LSL #16 BEQ EndPlotBlock LDRB r10,[r11,r5,LSR #14] AND r10,r10,r14,LSR #16 LDRB r9,[r11,r6,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #8 LDRB r9,[r11,r7,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #16 LDRB r9,[r11,r8,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #24 STR r10,[r12],#320 STR r10,[r12],#320 ADD r5,r5,r1 ADD r6,r6,r2 ADD r7,r7,r3 ADD r8,r8,r4 SUB r14,r14,#1 MOVS r10,r14,LSL #16 BEQ EndPlotBlock LDRB r10,[r11,r5,LSR #14] AND r10,r10,r14,LSR #16 LDRB r9,[r11,r6,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #8 LDRB r9,[r11,r7,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #16 LDRB r9,[r11,r8,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #24 STR r10,[r12],#320 STR r10,[r12],#320 ADD r5,r5,r1 ADD r6,r6,r2 ADD r7,r7,r3 ADD r8,r8,r4 SUB r14,r14,#1 MOVS r10,r14,LSL #16 BEQ EndPlotBlock LDRB r10,[r11,r5,LSR #14] AND r10,r10,r14,LSR #16 LDRB r9,[r11,r6,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #8 LDRB r9,[r11,r7,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #16 LDRB r9,[r11,r8,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #24 STR r10,[r12],#320 STR r10,[r12],#320 ADD r5,r5,r1 ADD r6,r6,r2 ADD r7,r7,r3 ADD r8,r8,r4 SUB r14,r14,#1 MOVS r10,r14,LSL #16 BEQ EndPlotBlock LDRB r10,[r11,r5,LSR #14] AND r10,r10,r14,LSR #16 LDRB r9,[r11,r6,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #8 LDRB r9,[r11,r7,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #16 LDRB r9,[r11,r8,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #24 STR r10,[r12],#320 STR r10,[r12],#320 ADD r5,r5,r1 ADD r6,r6,r2 ADD r7,r7,r3 ADD r8,r8,r4 SUB r14,r14,#1 MOVS r10,r14,LSL #16 BEQ EndPlotBlock LDRB r10,[r11,r5,LSR #14] AND r10,r10,r14,LSR #16 LDRB r9,[r11,r6,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #8 LDRB r9,[r11,r7,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #16 LDRB r9,[r11,r8,LSR #14] AND r9,r9,r14,LSR #16 ADD r10,r10,r9,LSL #24 STR r10,[r12],#320 STR r10,[r12],#320 ADD r5,r5,r1 ADD r6,r6,r2 ADD r7,r7,r3 ADD r8,r8,r4 SUB r14,r14,#1 MOVS r10,r14,LSL #16 BNE StartPlotBlock EndPlotBlock STMIA r0,{r5-r8} ; save gradient/data combos STR r12,[r0,#32] ; save screen address SUB r0,r0,#32 ; reset pointer to start of height data LDR r6,[r0,#72] ;draw lower section of line 1 MOV r5,r12 ; get old screen address LDR r1,[r0] ; get height of line 1 SUB r1,r1,r6 ; length = height - smallest height MOVS r1,r1,LSR #1 ; divide by 2 BEQ LowerLine2 LDR r2,[r0,#16] ; load gradient of line 1 LDR r3,[r0,#32] ; load gradient/data combo for line 1 LDR r4,[r0,#48] ; load data address of data for line 1 BL DrawByteLine LowerLine2 ;draw lower section of line 2 ADD r5,r12,#1 LDR r1,[r0,#4] ; get height of line 2 SUB r1,r1,r6 ; length = height - smallest height MOVS r1,r1,LSR #1 ; divide by 2 BEQ LowerLine3 LDR r2,[r0,#20] ; load gradient of line 2 LDR r3,[r0,#36] ; load gradient/data combo for line 2 LDR r4,[r0,#52] ; load data address of data for line 2 BL DrawByteLine LowerLine3 ;draw lower section of line 3 ADD r5,r12,#2 LDR r1,[r0,#8] ; get height of line 3 SUB r1,r1,r6 ; length = height - smallest height MOVS r1,r1,LSR #1 ; divide by 2 BEQ LowerLine4 LDR r2,[r0,#24] ; load gradient of line 3 LDR r3,[r0,#40] ; load gradient/data combo for line 3 LDR r4,[r0,#56] ; load data address of data for line 3 BL DrawByteLine LowerLine4 ;draw lower section of line 4 ADD r5,r12,#3 LDR r1,[r0,#12] ; get height of line 1 SUB r1,r1,r6 ; length = height - smallest height MOVS r1,r1,LSR #1 ; divide by 2 BEQ EndDSLine LDR r2,[r0,#28] ; load gradient of line 1 LDR r3,[r0,#44] ; load gradient/data combo for line 1 LDR r4,[r0,#60] ; load data address of data for line 1 BL DrawByteLine EndDSLine B OuterLoop EndOuterLoop LDMFD r13!,{r0-r12,pc} DBLineX DCB "DrawByteLine", 0 ALIGN DBLineY DCD &ff000000 + DBLineY - DBLineX ;scale line of graphics block to height value. ;on entry - ; r1 = length of line to draw ; r2 = gradient of line ; r3 = gradient counter plus data address ; r5 = screen address ; r14 = return address ; ;on exit - ; r1 = zero ; r2 = gradient of line ; r3 = gradient counter plus data address, updated ; r5 = updated screen address ; r14 = return address ; DrawByteLine ;store return location on stack STMFD r13!,{r14} ByteLineLoop ;load AND value LDR r14,[r0,#88] LDRB r10,[r11,r3,LSR #14] AND r10,r10,r14,LSR #16 STRB r10,[r5],#320 STRB r10,[r5],#320 ADD r3,r3,r2 SUBS r1,r1,#1 BEQ EndByteLine LDRB r10,[r11,r3,LSR #14] AND r10,r10,r14,LSR #16 STRB r10,[r5],#320 STRB r10,[r5],#320 ADD r3,r3,r2 SUBS r1,r1,#1 BEQ EndByteLine LDRB r10,[r11,r3,LSR #14] AND r10,r10,r14,LSR #16 STRB r10,[r5],#320 STRB r10,[r5],#320 ADD r3,r3,r2 SUBS r1,r1,#1 BEQ EndByteLine LDRB r10,[r11,r3,LSR #14] AND r10,r10,r14,LSR #16 STRB r10,[r5],#320 STRB r10,[r5],#320 ADD r3,r3,r2 SUBS r1,r1,#1 BEQ EndByteLine LDRB r10,[r11,r3,LSR #14] AND r10,r10,r14,LSR #16 STRB r10,[r5],#320 STRB r10,[r5],#320 ADD r3,r3,r2 SUBS r1,r1,#1 BEQ EndByteLine LDRB r10,[r11,r3,LSR #14] AND r10,r10,r14,LSR #16 STRB r10,[r5],#320 STRB r10,[r5],#320 ADD r3,r3,r2 SUBS r1,r1,#1 BEQ EndByteLine LDRB r10,[r11,r3,LSR #14] AND r10,r10,r14,LSR #16 STRB r10,[r5],#320 STRB r10,[r5],#320 ADD r3,r3,r2 SUBS r1,r1,#1 BEQ EndByteLine LDRB r10,[r11,r3,LSR #14] AND r10,r10,r14,LSR #16 STRB r10,[r5],#320 STRB r10,[r5],#320 ADD r3,r3,r2 SUBS r1,r1,#1 BNE ByteLineLoop EndByteLine LDMFD r13!,{r15} BRDScreenX DCB "BigRedrawScreen", 0 ALIGN BRDScreenY DCD &ff000000 + BRDScreenY - BRDScreenX ;draw background graphics. ;on entry - ; r0 = screen address |BigRedrawScreenVGA| STMFD r13!,{r0-r12,link} ;initial height value MOV r1,#128 ;load initial colour value into r2 & make word sized MOV r2,#44 ADD r2,r2,r2,LSL #8 ADD r2,r2,r2,LSL #16 ;move into other registers MOV r3,r2 MOV r4,r2 MOV r5,r2 MOV r6,r2 MOV r7,r2 MOV r8,r2 MOV r9,r2 MOV r10,r2 MOV r11,r2 BRDloop STMIA r0!,{r2-r11} ;plot one line of colour data on screen STMIA r0!,{r2-r11} STMIA r0!,{r2-r11} STMIA r0!,{r2-r11} STMIA r0!,{r3-r11} STMIA r0!,{r2-r11} STMIA r0!,{r2-r11} STMIA r0!,{r2-r11} SUBS r1,r1,#1 BNE BRDloop ;next height value MOV r1,#128 ;load next colour value into r2 & make word sized MOV r2,#46 ADD r2,r2,r2,LSL #8 ADD r2,r2,r2,LSL #16 ;move into other registers MOV r3,r2 MOV r4,r2 MOV r5,r2 MOV r6,r2 MOV r7,r2 MOV r8,r2 MOV r9,r2 MOV r10,r2 MOV r11,r2 BRDloopA STMIA r0!,{r2-r11} ;plot one line of colour data on screen STMIA r0!,{r2-r11} STMIA r0!,{r2-r11} STMIA r0!,{r2-r11} STMIA r0!,{r2-r11} STMIA r0!,{r2-r11} STMIA r0!,{r2-r11} STMIA r0!,{r2-r11} SUBS r1,r1,#1 BNE BRDloopA EndBRDScreen LDMFD r13!,{r0-r12,pc} END