implemented missing bitshift codegen (non-stack)

irmen · Jul 15, 2023 · 3841cef · 3841cef
1 parent b717f1c
commit 3841cef
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Showing 3 changed files with 105 additions and 32 deletions.
diff --git a/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt b/codeGenCpu6502/src/prog8/codegen/cpu6502/assignment/AssignmentAsmGen.kt
@@ -515,51 +515,84 @@ internal class AssignmentAsmGen(private val program: PtProgram,
         val shifts = expr.right.asConstInteger()
         if(shifts!=null) {
             val dt = expr.left.type
-            if(dt in ByteDatatypes && shifts in 0..7) {
+            if(dt in ByteDatatypes) {
                 val signed = dt == DataType.BYTE
                 assignExpressionToRegister(expr.left, RegisterOrPair.A, signed)
-                if(expr.operator=="<<") {
-                    repeat(shifts) {
-                        asmgen.out("  asl  a")
+                if(shifts in 0..7) {
+                    require(dt==DataType.UBYTE)
+                    if (expr.operator == "<<") {
+                        repeat(shifts) {
+                            asmgen.out("  asl  a")
+                        }
+                    } else {
+                        if (signed && shifts > 0) {
+                            asmgen.out("  ldy  #$shifts |  jsr  math.lsr_byte_A")
+                        } else {
+                            repeat(shifts) {
+                                asmgen.out("  lsr  a")
+                            }
+                        }
                     }
+                    assignRegisterByte(target, CpuRegister.A, signed)
+                    return true
                 } else {
-                    if(signed && shifts>0) {
-                        asmgen.out("  ldy  #$shifts |  jsr  math.lsr_byte_A")
+                    if(signed && expr.operator==">>") {
+                        TODO("signed byte >> overshift should have been compiled away?")
                     } else {
-                        repeat(shifts) {
-                            asmgen.out("  lsr  a")
-                        }
+                        asmgen.out("  lda  #0")
                     }
+                    assignRegisterByte(target, CpuRegister.A, signed)
+                    return true
                 }
-                assignRegisterByte(target, CpuRegister.A, signed)
-                return true
-            } else if(dt in WordDatatypes && shifts in 0..7) {
+            } else if(dt in WordDatatypes) {
                 val signed = dt == DataType.WORD
                 assignExpressionToRegister(expr.left, RegisterOrPair.AY, signed)
-                if(expr.operator=="<<") {
-                    if(shifts>0) {
-                        asmgen.out("  sty  P8ZP_SCRATCH_B1")
-                        repeat(shifts) {
-                            asmgen.out("  asl  a |  rol  P8ZP_SCRATCH_B1")
-                        }
-                        asmgen.out("  ldy  P8ZP_SCRATCH_B1")
-                    }
-                } else {
-                    if(signed) {
-                        // TODO("shift AY >> $shifts signed")
-                        return false
-                    } else {
+                if(shifts in 0..7) {
+                    if(expr.operator=="<<") {
                         if(shifts>0) {
                             asmgen.out("  sty  P8ZP_SCRATCH_B1")
                             repeat(shifts) {
-                                asmgen.out("  lsr  P8ZP_SCRATCH_B1 |  ror  a")
+                                asmgen.out("  asl  a |  rol  P8ZP_SCRATCH_B1")
                             }
                             asmgen.out("  ldy  P8ZP_SCRATCH_B1")
                         }
+                    } else {
+                        if(signed && shifts>0) {
+                            asmgen.out("  ldx  #$shifts |  jsr  math.lsr_word_AY")
+                        } else {
+                            if(shifts>0) {
+                                asmgen.out("  sty  P8ZP_SCRATCH_B1")
+                                repeat(shifts) {
+                                    asmgen.out("  lsr  P8ZP_SCRATCH_B1 |  ror  a")
+                                }
+                                asmgen.out("  ldy  P8ZP_SCRATCH_B1")
+                            }
+                        }
+                    }
+                    assignRegisterpairWord(target, RegisterOrPair.AY)
+                    return true
+                } else if (shifts in 8..15) {
+                    if(expr.operator == "<<") {
+                        // msb = lsb << (shifts-8),   lsb = 0
+                        repeat(shifts-8) {
+                            asmgen.out("  asl  a")
+                        }
+                        asmgen.out("  tay |  lda  #0")
+                    } else {
+                        asmgen.out("  ldx  #$shifts |  jsr  math.lsr_word_AY")
                     }
+                    assignRegisterpairWord(target, RegisterOrPair.AY)
+                    return true
+                }
+                else {
+                    if(signed && expr.operator==">>") {
+                        TODO("signed word >> overshift should have been compiled away?")
+                    } else {
+                        asmgen.out("  lda  #0 |  ldy  #0")
+                    }
+                    assignRegisterpairWord(target, RegisterOrPair.AY)
+                    return true
                 }
-                assignRegisterpairWord(target, RegisterOrPair.AY)
-                return true
             }
         }
         return false

diff --git a/compiler/res/prog8lib/math.asm b/compiler/res/prog8lib/math.asm
@@ -749,20 +749,42 @@ mul_word_640	.proc
 ; support for bit shifting that is too large to be unrolled:
 
 lsr_byte_A	.proc
-		; -- lsr signed byte in A times the value in Y (assume >0)
+		; -- lsr signed byte in A times the value in Y (>1)
 		cmp  #0
 		bmi  _negative
 -		lsr  a
 		dey
 		bne  -
 		rts
-_negative	lsr  a
-		ora  #$80
+_negative	sec
+		ror  a
 		dey
 		bne  _negative
 		rts
 		.pend
 
+lsr_word_AY     .proc
+		; -- lsr signed word in AY times the value in X (>1)
+		sta  P8ZP_SCRATCH_B1
+		tya
+		bmi  _negative
+-		lsr  a
+		ror  P8ZP_SCRATCH_B1
+		dex
+		bne  -
+		tay
+		lda  P8ZP_SCRATCH_B1
+		rts
+_negative       sec
+		ror  a
+		ror  P8ZP_SCRATCH_B1
+		dex
+		bne  _negative
+		tay
+		lda  P8ZP_SCRATCH_B1
+		rts
+		.pend
+
 
 square          .proc
 ; -- calculate square root of signed word in AY, result in AY

diff --git a/examples/test.p8 b/examples/test.p8
@@ -5,9 +5,27 @@ main
 {
     sub start()
     {
-        ; uword zc = $ea31
         word zc = -5583
+        txt.print_w(zc)
+        txt.spc()
+        txt.print_w(zc>>10)  ; -6
+        txt.nl()
+
+        txt.print_w(zc)
+        txt.spc()
+        txt.print_w(zc>>4)   ; -349
+        txt.nl()
+
+        txt.print_w(zc)
+        txt.spc()
+        txt.print_w(zc>>10)  ; -6
+        txt.nl()
+
         cx16.r1L = (zc>>10) as ubyte
         txt.print_ub(cx16.r1L)      ; 250
+        txt.nl()
+        cx16.r1L = (zc>>4) as ubyte
+        txt.print_ub(cx16.r1L)      ; 163
+        txt.nl()
     }
 }